Paula Patton attended the Grammy Awards with Robin Thicke "as a favour" last month.
The duo agreed to put on a united front before they announced their split on Monday (24.02.14), after almost nine years of marriage, but they began "unravelling a long time" ago and their relationship reportedly got rockier after Miley Cyrus twerked against the 'Blurred Lines' hitmaker at the MTV Video Music Awards (VMAs) last August.
A source told UsMagazine.com: "The Miley Cyrus fiasco was a big test of their relationship. He asked her to help him out as a friend and a wife, and defend him and the performance. He begged her to speak out for him and be there for him.
"She agreed to be the good wife after he begged and pleaded. Then he asked her to stick with him through awards season, and she agreed. She attended the Grammys with him as a favour."
Paula, 38, frequently voiced her support for raunchy performance and previously said: "They rehearsed for three days. Robin told me in advance. I thought it was great."
The 'Baggage Claim' star also defended Robin, 36, after he was photographed grabbing a model's butt at a VMA after-party and was accused of cheating on her.
But the insider said: "Their marriage was unravelling a long time. It is not a shock to Robin or Paula, and it is something they have discussed for a long time."
The couple, who have a three-year-old son, Julian, together, released a joint statement on Monday that read: "We will always love each other and be best friends. However, we have mutually decided to separate at this time."

Coldplay shocked fans by unveiling a new single and video today (25.02.14).
The 'Paradise' hitmakers posted the video for the new track 'Midnight' on their VEVO site, after teasing fans on Twitter there was "something new" to come.
The monochrome video, directed by Mary Wigmore, shows frontman Chris Martin and band mates Jonny Buckland, Guy Berryman, Will Champion, walking through a woodland, as the scene flashes different colours and a fox moves among the grass.
The atmospheric track is a big departure from the band's usual melodies and catchy riffs, swapping guitar and piano for synthesisers and taking inspiration from electronic music.
Fans have compared their new sound to American indie folk band Bon Iver and the band are believed to be working on their sixth studio album, the follow-up to 'Mylo Xyloto' in 2011, which sold over eight million copies worldwide.
Chris, 36, revealed they had started work on the record back in 2012 and said he was "so fired up about the band's future", adding: 'I'm fortunate to do what I do and no way do I want to stop."
Last year, the group revealed their track 'Atlas', which was taken from the soundtrack for 'The Hunger Games: Catching Fire', and they played an intimate show at a pub in Somerset in December where they treated punters to a number of hits.

Kate Garraway isn't sure about doing more reality TV.
The 'Daybreak' presenter - who was announced as one of the new presenters on Smooth Radio yesterday (24.02.14) - is ruling out appearances on ITV diving show 'Splash!' and Channel 4's Winter Olympics-themed 'The Jump' following her stint on 'Strictly Come Dancing' in 2007.
Speaking to BANG Showbiz at the launch of the new Smooth Radio in London, she said: "I'm not sure really. When you look at some of the ones that have been on recently ... oh, 'Splash!' looks like agony, doesn't it?
"And 'The Jump' - oh my goodness, that looks so hard.
"I think I got into enough trouble in 'Strictly' with bits of me getting broken and injured so I think I should stay away from some of those shows."
The 48-year-old TV star has joined Smooth Radio's new star-studded line-up along with 'Loose Women' star Myleene Klass and former 'Holby City' actress Tina Hobley.
Kate is looking forward to hosting her new mid-morning weekday show, which begins on March 3 at 10am.
She said: "I've always been interested in radio and I think it's a brilliant medium. I think it's very free. With radio, there's just you, a mic and some music. It's more intimate."

George Harrison has been honoured by The Beach Boys' Mike Love on his 71st birthday today (25.02.14).
The late Beatles' musician has been remembered by his friend with a previously unreleased track, 'Pisces Brothers', which was inspired by the Famous Four's trip to India with Mike in 1968, after they received an invitation from the Maharishi, Mahesh Yogi.
In a statement, Mike said: "This being the 50th anniversary of The Beatles coming to America, I wanted to commemorate this incredibly significant trip we all took together to India, at the Maharishi's invitation.
Mike described the trip as "enormously influential" for him and George, who died of cancer in 2001, and his band mates - Paul McCartney, Ringo Starr and John Lennon.
They were also joined by songwriter Donovan and American actress, Mia Farrow, and attended an advanced Transcendental Meditation (TM) training session.
Mike, 72, said: "The song is really sentimental for me, and meant to honour George Harrison's remarkable contribution to music. And how, in this one moment in time, we got together, as the song says, not fortune or for fame, but for enlightenment."
The title of the song makes reference to the astrological sign the pair share, while Mike continues to practice the meditation techniques he was taught during his trip to India.

'The Valleys' girls are fighting over newcomer Jack Watkins.
He may have only been part of the MTV reality series for a matter of minutes but the newest cast member is already ruffling feathers on the hit MTV show.
The 24-year-old stripper is welcomed onto the show during tonight's (25.02.14) series three opener, immediately sparking competition between the girls - Carley Belmonte, Lateysha Grace and Jenna Jonathan - as they vie for his attention.
21-year-old model Lateysha is the first to pounce on newbie Jack, pecking him on the cheek and saying: "One kiss from Teesh, to keep him on the leash."
But her best friend Jenna is quick to step in, saying: "If Teesha's gonna flirt up the new boy, so am I."
Carley, 23, adds: "He's gonna be a naughty addition to the house."
Fortunately for fans of the reality TV show - which is known for its characters' drunken antics and on-screen rows - Jack's trouble-stirring doesn't stop with the girls.
Male castmates Darren Chidgey and twins Anthony and Jason Suminski are noticeably rattled by the appearance of a new hunk and are left reeling with jealousy after the girls shower him with kisses.
Chidgey asks: "Who the hell does this guy think he is?"
The third series of 'The Valleys' airs tonight on MTV at 10pm.

Angelina Jolie wants to teach her children about the "strength of the human spirit".
The 38-year-old actress - who raises kids Maddox, 12, Pax, 10, Zahara, eight, Shiloh, seven, and twins Knox and Vivienne, five, with fiance Brad Pitt - has stepped behind the camera again for 'Unbroken', which tells the tale of World War II hero and former Olympic distance runner Louis Zamperini and she is hopeful the movie will send a positive message.
Angelina said: "For me, I think Louis has been very clear about what his message is. And I think, for my children, and for everybody in the world, I want to be able to say, it can seem dark, and it can seem hopeless, and it can seem very overwhelming, but the resilience and the strength of the human spirit is an extraordinary thing."
'Unbroken' marks Angelina's third venture into directing and she knew whatever project she took on had to mean something significant to her.
Speaking on the 'Today' show, she said: "I wanted to direct something again, but I just wasn't sure what. And it had to be something that I would love and care about, because it takes much more time away from your family, and much more effort than acting."
And the 'Maleficent' star - who lives in the same Los Angeles neighbourhood as Louis, 97 - felt a "responsibility" to the story because of the bond she forged with the war hero.
She said: "[It's] such a huge responsibility to get it right. Because I love [Louis] so much. And because he's helped me so much in my life."

Scarlett Johansson follows her "instincts".
The 29-year-old actress insists she doesn't worry about what audiences or movie executives think of her career choices as she always puts her "artistic integrity" first.
In an extract from her interview with Dazed magazine obtained by JustJared.com, she said: "You have to have your own artistic integrity, and then you don't cave in to pressure. I don't know what the audience or the studio are going to like. I just follow my instincts."
The 'Avengers' actress - who was previously married to Ryan Reynolds and is now engaged to Romain Dauriac - also spoke of how she has come to terms with her figure being "objectified".
She said: "How could I wake up every day and be a normal person if I was completely aware that my image was being manipulated on a global platform. How could I sleep? You have to have peace of mind. You've got to be able to protect those things. How else could you exist? You'd go crazy, anybody would go crazy..."

Julianne Moore saw "all kinds of boobs" when she took her daughter to a spa.
The 53-year-old actress - who has children Caleb, 16, and Liv, 11, with husband Bart Freundlich - says her youngest child was fascinated by the different female bodies she saw when they relaxed in a ladies-only steam room.
She said: "Liv loves to go to spas but, because she's 11, she can't get into any of the fancy ones. You have to be older, like a teenager."
Explaining they often visit a child-friendly franchise called Spa Castle, she added: "They're enormous. Floors and floors of hot tubs and steam rooms.
"[We went in the female-only steam room where] everyone's naked, so Liv got to see all these different types of bodies.
"She said, 'Mom, I didn't know that there are big boobs, and little boobs and round boobs and pointy boobs and all kinds of boobs. And then there was this lady -- I thought she was wearing underpants [but she wasn't] and I was like, 'Yeah, there's that, too.'"
The 'Non-Stop' actress also admitted she hates being referred to as "ma'am" as the polite formal address makes her feel like an old lady.
Speaking on 'Chelsea Lately', she said: "It's terrible. You may as well say, like, 'Hey, old lady, do you need some help getting up the steps?' Or, 'Can I cut your food for you, old lady?'"

Katy Perry and John Mayer are planning to marry in June.
The couple - who have been dating around 18 months - sparked speculation they were engaged when the 'Prism' singer stepped out on Valentine's Day (14.02.14) wearing a ring on her engagement finger and insiders say they have already found the perfect venue and asked the pop star's pastor father, Keith Hudson, to officiate their nuptials.
A source told Grazia magazine: "They'd love a June wedding. They want to get married at the San Ysidro Ranch in Katy's home town of Santa Barbara."
The ranch previously played host to the wedding of Gwyneth Paltrow and Chris Martin in 2003, and was also where John F. Kennedy and wife Jackie spent their honeymoon.
Superstition has already pointed to Katy - who was previously married to comedian Russell Brand, who she divorced in 2012 - and John marrying, after she caught one of the bouquets of flowers thrown by a couple married during Macklemore and Ryan Lewis' performance of 'Same Love' at the Grammy Awards. Tradition follows that the person who catches the bouquet will marry next.
Sources have also said John referred to Katy as his "wife" when they were on set for a joint TV appearance last year.

Sweden's King and Queen have met their new granddaughter.
King Carl XVI Gustaf and Queen Silvia jumped on a plane to meet the tiny tot, who was born to their daughter Princess Madeleine and her husband Chris O'Neill, last Thursday (20.02.14) in New York City.
The new parents reportedly took their baby - who is fifth-in-line to the throne - home on Saturday (22.02.14) after they welcomed her into the world at the New York Presbyterian Hospital two days before.
Meanwhile, the King and Queen were keen to make the most of their trip to the big apple as they were spotted doing a bit of shopping at Bloomingdale's on Sunday (23.02.14), before meeting their proud son-in-law Chris for a bite to eat at Amaranth in Manhattan.
The newborn is yet to be given a name, but her title is to be announced after King Carl has met with the cabinet.
The King and Queen announced on Friday that they were overjoyed by the news of the new arrival.
They said: "We know today both happiness and warm thanks. Our joy is great. We wish now that Princess Madeleine and Christopher get peace and quiet and can take advantage of this unique time with her little daughter."
Madeleine and Chris currently reside in New York, but it is believed they will return to Sweden with the baby in a few weeks.

Dara O'Briain worries the BBC's decision to ban all-male panels will lead to females being considered the "token woman".
The 'Mock the Week' host host has hit back at BBC head of television Danny Cohen's recent ban on all-male panels on its comedy shows, insisting it would have been better to make such changes behind the scenes.
He explained: "I wouldn't have announced it, is what I'd say. Because it means [comediennes] Katherine Ryan or Holly Walsh, who've been on millions of times, will suddenly look like the token woman. It would have been better if it had evolved without showing your workings, if you know what I mean.
"Legislating for a token woman isn't much help."
The 42-year-old comic claimed female panellists were already being prioritised by 'Mock the Week's' all-female commissioning editors to ensure diversity on the show.
He said: "We bring through female comics earlier than we do male comics because there is such a tiny pool of female stand-ups. But this makes it even tougher for them."
Dara also claims stand-up comedy naturally tends to draw more male comics than female comics.
He added to Radio Times magazine: "A certain number of women want to go into comedy, and they should be cherished and nurtured, but you're not going to shift the fact that loads more men want to do it.
"It's remarkable that this amount of time is spent debating women on comedy shows rather than, say, 'Question Time'."

Ray Quinn feels like he's "blagging" his way through 'Dancing on Ice'.
The former 'X Factor' contestant is a hot favourite to win the all-stars series of the ITV skating competition after wowing the judges every week, however, he admits he isn't as confident on the ice as he seems.
Appearing on ITV's 'Daybreak' today (25.02.14), he said: "I'm definitely blagging it. You're living on the edge on the skates. There's so much to think about. It either happens or it doesn't, that's the thing."
Meanwhile, Ray - who got into shape for the new series using Forza T5 fat burners, which helped him drop two stone in eight weeks - says he is living in the moment and isn't considering the thought he and skating partner Maria Filippov may win the series.
He said: "I try not to think about it, to be honest. The nerves are there anyway and you're anxious about going out and doing something that's out of your comfort zone anyway so there's a lot to think about. It sounds stupid but I live like a dog - I live in the moment so I live in what is happening now and what I need to do now, and then once it's done it's in the pocket."