A man in grief, angry, unhinged, or feeling newly free of cumulative stress can be a vulnerable target for an outside person, or even an unthinking seeker of temporary escape.
People in unstable situations often make in-the-moment decisions that have nothing to do with what they may need or want as time elapses.
They are at a loss when it happens, but still feel attached to their history, friends, children, financial situation, mutual families, and a deeper caring.
After a time apart, they realize that they want to make the relationship work and are highly motivated to make that happen.
In the midst of a separation, especially if many other people want that relationship to keep going, he may be overwhelmed with indecision and unable to see clearly what is best.