Following news of the couple's split on Thursday, a source tells ET that the end of their more than four-year relationship "is no surprise."
"They haven't been getting along for quite some time and seemed to be holding on to their relationship for the sake of their daughter," the source says, referring to the couple's 2-year-old daughter, Lea.
"Those closest to them had high hopes that when Bradley completed promoting A Star is Born, they would find time to work out their differences, but things only got worse," the source continues. "Some of their friends feel they never truly got a chance to know each other outside of being a family, and it was just all too much too fast."
According to the source, Shayk "had high hopes" for her life with Cooper but was ultimately "unhappy" with the 44-year-old actor's work schedule.
"Irina truly had high hopes for their future together and felt once the baby was born they would find the time to marry but that never came to fruition," the source says of the 33-year-old model. "She wanted more from Bradley in every way. But she was unhappy and felt he spent too much time working."
"Recently Irina decided enough is enough. She didn't feel she was getting the level of commitment she wanted and the endless fighting made their life unbearable," the source adds. "They are very different people and once they realized it was the baby that was holding them together, it was time to call it quits."
Earlier this week, a source told ET that Shayk and Cooper had "been unhappy in their relationship for some time."
"Their troubles have been going on for quite some time and they even considered splitting during the release of the movie," the source said of A Star Is Born. "They talked things through a great deal and seemed to hold off and keep up appearances for the time being. It was recommended they delay a split at what seemed to be the peak of his career because the negative attention would take away from the excitement of the release."
After news broke of their split, Shayk was spotted leaving her house solo with a suitcase before arriving at the airport with a smile on her face.
Watch the video below for more on the former couple.