Katie Holmes had reportedly grown tired of Tom Cruise always putting work before family.
The former 'Dawson's Creek' actress - who filed for divorce from the 50-year-old actor last week - was said be fed up with how Tom was often away from home and never made her or their six-year-old daughter, Suri, his priority.
A source said: ''They had problems for a while. His career came first, and Katie was no longer happy. She wanted him to stay home and spend time together. But Tom has always been a movie star, he knows nothing else. This is a good father and good husband, when present, but ... the work comes first.''
Katie, 33, was also keen for little Suri to have a normal childhood and knew if she stayed with Tom she wouldn't be able to because he is such a big follower of the controversial religion Scientology.
The source added to E! Online: ''She left him because she wanted a better life for herself and her daughter. Suri has no friends. She has no normal life, and it became increasingly obvious, as she got older.
''Katie wants a project where she will remain in a fixed location, where Suri will go to school, have friends, meet children to play, all these things she doesn't do right now. Katie was unhappy in her marriage, so she decided to end it so that her daughter had a happier life.''
It has been claimed Katie left Tom as she feared he wanted to send Suri to a boot camp for the cult religion.