Bradley Cooper and Irina Shayk were "living totally separate lives" before their split.
The 33-year-old supermodel reportedly decided to end her relationship with the 'A Star is Born' star - with whom she has two-year-old daughter Lea De Seine - at the end of last month because the pair rarely spent any time together.
A source told PEOPLE: "[Irina is] not focused on the celebrity part, or on the fame - she just wants to protect her family. Bradley is very into work and is trying to take advantage of every career opportunity right now. They spent a lot of time apart.
"They were living totally separate lives. If he was in L.A., she's out of town, and if she was in town, he was out of town."
It has also been reported that the pair tried to save their four-year relationship, for the sake of their young daughter but that they failed to "make a life together outside of the child".