Michael Sheen split from Rachel McAdams because they had ''different visions for the future''.
The 'Midnight in Paris' co-stars were reported to have ended their two-year romance earlier this week, and insiders say it is because the pair want different things from the future.
A source told People: ''Rachel wants to settle down and is dreaming of having a family. Michael always seemed content with their relationship. Since he already has a daughter he feels no need to have more children. He wants to focus on his career.''
Michael - who has 14-year-old Lily with ex-girlfriend Kate Beckinsale - and Rachel, 34, are still on good terms, but were unable to reconcile the differences in their relationship.
The source added: ''They still have some contact and are friendly.
''They tried to work things out, but at the end they just couldn't agree. It caused some frustration and they thought it was better to go separate ways.''
Despite their differences, friends have said they are hopeful the 45-year-old actor and the 'Notebook' star will reconcile.
A friend said: ''It's likely not permanent. Temporary hiccup.''