Taylor Swift lost her virginity to Jake Gyllenhaal.
The 'We Are Never Ever Getting Back Together' star was initially waiting until she was married to have sex, but was so smitten with the 'Brokeback Mountain' star she went to bed with him after a few months of dating.
A source told RadarOnline.com: "She thought she was going to marry Jake, that's how in love she was with him."
However, things stated to go wrong a little later when Jake, 33, didn't make the star's 21st birthday party at her family home in Nashville, Tennessee, in December 2010.
The source added: "The day before - all was set - he was coming, no issues. But the day of, she doesn't hear from him at all. No texts, no calls.
"Taylor thought maybe he was planning some sort of surprise. Nope. He didn't show up and she locked herself in the bathroom and cried the entire night."
The source says their breakup shortly after inspired her last album, 'Red', in particular the track 'The Moment I Knew', which features the lyrics: "You should've been there, Should've burst through the door ... You said you'd be here."
The insider said: "Her breakup with Jake inspired every word of 'Red'. The song that specifically references this 'event' is 'The Moment I Knew.' They lyrics are all about her birthday party and Jake not showing up."
Despite the source's assertions, Taylor has previously insisted the track 'I Knew You Were Trouble' from the same album was about another of her ex-boyfriends, Harry Styles.
The 24-year-old star is famous for penning tracks about her famous exes, with her song 'Dear John' widely believed to be about her short-lived relationship with John Mayer. She has also dated Taylor Lautner and Joe Jonas.

Lil' Kim is having a baby boy.
The rapper announced she is to have her first child last week, and the baby's father, rapper Mr. Papers, says it will be a boy.
He told RadarOnline.com: "That's my baby... He'll be taken care of."
Kim - who is believed to be four-and-a-half months pregnant - had initially declined to say who the father was when she unveiled her baby bump at New York Fashion Week on February 12 but Mr. Papers says they are an item.
He added: "We together."
The rapper - whose real name is unknown - has previously said he plans for his son to enjoy the finer things in life.
He said: "That baby is going to be well taken care of... rocking Tom Ford, Versace - even the stroller will be designer."
'Thug Luv' star Kim, 39, has said she is "in heaven" over her pregnancy and has been getting cravings.
She said: "[I'm eating] Pizza! Everyday, pizza! A lot of vegetable pizza, because before I didn't eat vegetable pizza as much, but now I'm craving the vegetables."
Kim has also had to change her notoriously outrageous wardrobe to accommodate her growing bump.
She added: "I can't wear corsets and all my favourite sexy clothes [anymore]. But it's a very beautiful thing and I'm so thrilled."

Justin Bieber has been looking at an $11 million mansion in Atlanta.
The 'Confident' singer has been to view the huge property in the exclusive Buckhead district - where his mentor, Usher, lives - and is keen to move to the city to be close to its famous hip-hop scene.
The house the singer is interested in has seven bedrooms and is16,000 square feet in size, according to TMZ.com.
Justin, 19, is said to be selling his home in Calabasas, California, after falling out with his neighbours over his partying and loud music, which came to a head with an incident where one of his neighbour's houses was egged, causing up to $20,000 of damage. The matter is currently being investigated by the District Attorney and could result in charges brought against the star.
Criteria listed for any potential new home for Justin includes the property must not be visible from the street and must preferably have at least five acres around it and be a minimum of 10,000 square feet inside.
The singer is said to be looking at houses listed for between $4 and $10 million and is also searching for a second home in the Los Angeles area, as well as looking at 20 acre estates in the Hidden Valley area.
Justin recently paid a visit to Atlanta where he was seen partying with P. Diddy, T.I. and Rick Ross.
While in the city he wrote on Twitter: "Back in my second home. Good to be back. Focused on building up positive energy"
Atlanta was the first place Justin - who was raised in London, Ontario - lived when he moved to the US from Canada to embark on his music career.

Ed Sheeran celebrated his birthday with sausages and mash.
The 'Small Bump' singer turned 23 today (17.02.14) and marked the occasion by having a traditional British dinner and reminiscing on past times with his family.
He wrote on Twitter: "So many lovely birthday messages, sorry i can't reply to all of them. gonna eat sausage and mash and watch old family videos tonight x (sic)."
The singer-songwriter also showed off a few of the presents he'd been sent including a Huggable Pizza Cushion - shaped to look like the fast food treat - which he described as "possibly the coolest birthday present ever", a pin badge, a mug with "You Mug" written on it and a live DVD of boy band Busted.
Ed's friend and former tour buddy Taylor Swift also weighed in with a jokey birthday greeting, posting: "HAPPYBIRTHDAY @edsheeran! Now let's take a moment to reflect back on the best outfit you've ever worn (sic)."
With the post she included a picture of Ed - famed for almost always appearing in jeans and a T-shirt - wearing a shirt with a jumper knotted at the arms and worn around his neck.
Ed is currently enjoying some down time after touring the US with Taylor last year and recording his new album, which is set for release later in 2014.

Ariana Grande has recorded a track with Chris Brown.
The 'Baby I' singer has been in the studio with the controversial star - who is currently in rehab for anger management - and they announced their collaboration by sharing some of its lyrics on Twitter.
Chris tweeted: "I dug a single seed into the ground, I hope it grows,"
Ariana responded: "In a year or two if you're around, you'll see a rose."
When asked what her favourite song at the moment is by a fan, Ariana teased: "a song u haven't heard that is coming out in march (sic)."
The 20-year-old singer's manager, Scooter Braun, then confirmed the pair were teaming up, writing: "@ArianaGrande that was an amazing session. Excited for this incredible duet on the way 🙂 (sic)"
The song could help revitalise Chris' musical career, which has taken a back seat while he sorts out his personal issues, with his sixth album, 'X', still not on sale, despite four singles being released from it.
Chris, 24, has been on probation since his 2009 assault of then-girlfriend Rihanna, which was revoked last December, following an alleged assault in Washington D.C., a case which is still awaiting trial.
However, since attending rehab the 'Fine China' star's behaviour has improved, according to a report from his probation officer.
The report stated: "The clinical and medical team have witnessed very positive change in Mr. Brown since his psychotropic medications have been changed and he has been taken off medical marijuana. His ability to emotionally regulate himself has improved markedly."

Bradley Cooper didn't wear underwear when he met US President Barack Obama.
The 'Silver Linings Playbook' actor and his girlfriend, Suki Waterhouse, met the US premiere at a state dinner last week, but he says gaining weight for a new role left him with no room for boxer shorts.
Speaking to talk show host Ellen DeGeneres, he said: "I'm prepping for new movie and I'm trying to gain weight fast, I've gained about 15 pounds in four weeks and nothing fits me anymore. I wore the tuxedo I wore to the Golden Globes and I just sort of threw it in the bag and went to Washington D.C.
"I'm getting dressed, like, 10 minutes before I was supposed to go and literally the pants go up to like here [halfway up his thigh].
"So I had to go commando because there was no room at all. I did. I had to... So it was really great. And you have to walk up the stairs and it was a nightmare. But I made it through."
Bradley, 39, is nominated for Best Supporting Actor for his role in 'American Hustle' at the Oscars on March 2 - his second year nominated for the award in a row - and is having trouble deciding between taking his sister and his mother with him, so appealed to Ellen, the awards' host, for help.
He explained: "I'm trying to take more than one person. My sister's coming from North Carolina ... How can I [choose?]. Maybe they'll sit them at the top, maybe there's some seats at the top?"
Ellen initially sounded doubtful, but later added: "I'll see what I can do for you."

Miley Cyrus stuffed a fan's thong in her mouth while performing on Sunday night (16.12.14).
The 'Wrecking Ball' singer surprised the audience at her Bangerz Tour show in Tacoma, North West US, when she spotted the red undergarment thrown by a member of the audience then proceeded to wrap it around her microphone and put it in her mouth.
A stunned audience member wrote on twitter: "OMFG SOMEONE JUST THREW THEIR THONG ON STAGE AND MILEY PUT IT IN HER MOUTH!!!! (sic)"
The singer's wild antics didn't stop there and at another point in the show she straddled one of her female backing dancers, and writhed around her, wearing a bright red fluffy waistcoat.
The Bangerz Tour kicked off in Vancouver, Canada on February 14, and features a number of surreal moments including Miley riding a giant hot dog, rubbing her crotch and sucking on a foam finger, as well as plenty of her signature moves - sticking out her tongue and Twerking, the butt-shaking dance move she popularised last year.
Despite the controversies, Miley, 21, has said she wants the show to be "educational" for children.
She said: "I hope people open their minds and they look at my tour as something that I do feel is educational for kids.
"Because I think a lot of people aren't exposed to art enough and that's something that I had to learn about ... they pretty much teach you everything in the world as black and white and I want my fans to walk away knowing more about the art that inspires me."

Mariah Carey's daughter will appear on her new album.
The 'You're Mine (Eternal)' singer - who has two-year-old twins Moroccan and Monroe with husband Nick Cannon - has been recording her little girl "ad libbing" after she began mimicking the lyrics from one of her new songs, and says the clips will feature on her forthcoming LP.
She said: "It's a song that I wrote with Bryan-Michael Cox and Jermaine Dupri. There's a part that Jermaine says on the song that [the kids] loved, and Monroe started to say it.
"I kept having to get my iPhone and record her. So I have all these different takes of her saying things, singing things. Then I'd be like, 'This is your new ad lib -- learn it!' I have to make it fun for her."
The 'Hero' hitmaker insists both of her children are already showing signs of musical talent.
She told People: "Well, they started singing and talking simultaneously. It's hard to explain. That sounds like a lie, but it's true. They're both so musical."
And Mariah claims she is a "tough" mother who won't let her kids watch non-educational programming - unless she is relaxing and watching TV with them.
She said: "Their favourite thing is, 'Lie down, Mommy.' Meaning, 'Lay with me and watch a movie.' Because otherwise they have to watch Your Baby Can Read or something educational. I'm a tough task-master like that."

'Downton Abbey's' Laura Carmichael thinks her character is the Carrie Bradshaw of the 1920s.
The actress, who plays Lady Edith Crawley in the period drama, imagines her to be like Sarah Jessica Parker's 'Sex And The City' alter ego, because she writes a column for a newspaper about women's issues, despite it not being mentioned often in the show.
Laura told vulture.com: "I do love to think of her in my head as Carrie Bradshaw of the 20s. She's got a column on being a modern woman. Probably far less racy."
Although Edith's work isn't mentioned much on the show, it is important to Laura that it remains a part of the character.
She explained: "Her writing was still going on this season, and I kept checking with the producers to make sure of it. She would submit an article monthly to the newspaper, and it would have been this casual column. It was pretty common of women of her status."
Lady Edith has recently been left heartbroken in the show after falling for editor Michael Gregson, who disappeared after she found out she was pregnant.
When asked if the tone of her writing would have changed in her newspaper columns, Laura joked: "Can you imagine? 'I couldn't help but wonder... where has he gone?' It writes itself."
Laura says Lady Edith chooses what she wants rather than what is expected of her and she is proud of her character
She added: "I love that Edith has become very brave. She's forced to along her journey, being left at the altar and such. I think she would have been the most traditional of all the daughters.
"In the end, life was harder on her and it falls on her to become a professional woman and write for a newspaper and find a different path for herself. That's really cool."

Tori Spelling has claimed Farrah Fawcett has sent her a message from beyond the grave.
The 40-year-old actress was seeing TV psychic John Edward in the hope of contacting her late father Aaron Spelling - who died in 2006 aged 83 - but was instead contacted by the late actress, who starred in the producer's show 'Charlie's Angels'.
Tori said: "Farrah Fawcett came through in my reading loud and clear. It was real."
Tori used to live near Farrah - who died of cancer aged 62 in 2009 -
and says her former neighbour wanted her to pass a message on to her former partner Ryan O'Neal and their son Redmond about "what she was doing and what was going on."
The reality TV star - who has children Liam, six, Stella, five, Hattie, two, and Finn, 17 months, with husband Dean McDermott - later wrote a letter to Ryan about her psychic encounter, but has not heard back from the 72-year-old actor.
She added to 'Access Hollywood': "She gave very specific details about things to tell them.
"I haven't heard from Ryan. I am hoping he understood what I was trying to say and doesn't think I'm some loony."

Lisa Marie Presley is a "scary" mother.
The 46-year-old singer is very protective of her kids, Riley, 24, and 21-year-old Benjamin - who she had with first husband Danny Keough - and five-year-old twins Harper and Finley, who she has with spouse Michael Lockwood.
Speaking on 'Oprah: Where Are They Now?' she said: "I'm very, very much a very strong and intense lioness mother. Very scary, intense lioness mother."
Lisa Marie admits she is so protective, her older children used to keep things from her.
She added: "If something happened to them or someone was bullying or doing something, they knew that I would be very proactive in dealing with it, so they wouldn't tell me a lot. So I'm very, very protective number one. Also, [I] want to be their friend and protect them, but also get them to learn how to live in the world that we're living in."
Lisa Marie also spoke of how she has taught her kids they will be "loved" because of their famous grandfather, late singing legend Elvis Presley.
She added: "They kind of know, because they heard music and stuff and they've gotten the idea. I just say he was a very special person who sang and he touched a lot of people in the world and, and people loved him and they're going to love you because of him. And they kind of understand that."

Britain's Prince William has called for all the ivory in Buckingham Palace to be destroyed.
The Duke of Cambridge recently launched the charity United for Wildlife - which aims to end the illegal wildlife trade - and the second-in-line to the throne now revealed that he wants all of the ivory at the royal residence to be removed to encourage people to take up the fight against poaching.
The royal collection is comprised of approximately 1,200 items spanning over hundreds of years, including a throne from India, and William hopes if the British royal family set an example it will persuade other heads of state to follow suit.
Leading primatologist Jane Goodall told the Independent on Sunday newspaper that William - whose wife is Duchess Catherine - had personally informed her he would "like to see all the ivory owned by Buckingham Palace destroyed".
The prince's wish comes just days after he attended the world's largest ever conference on the issue at London's Zoological Society which called for an end to the £12 billion illegal trade in animals and their body parts. The campaign was highly successful last year with at least 45 tons of ivory seized in what's believed to have been the largest haul in 250 years.
William's father Prince Charles has also been encouraging the move and is believed to have asked for ivory items at Clarence House and his Highgrove property to be put out of sight over the last few years but experts say William's plans for destruction will send a powerful message to the world.
William, 31, attracted criticism ahead of his speech at United for Wildlife when he photographed hunting for boar in Spain with his brother Prince Harry, 29.