There is also the simple matter that if he is aware that relationships can go wrong, he might be more shy of going into them. This might not have anythin to do with you are even your husband,, but might simply be his experiences going bak to the breakup. Also, a 21 year old has a lot to get straightened out in his head. He is not completely over a lot of the adolescnet stugff, and if he has a father who is being unreasonalble about somethings, it will take a little longer for him to get that sorted out. It will take him a bit longer to decide what kind of man he will be. He might not be blaming you for anything, but he might have to turn tinto himslef more for advice on what to do as a man when questions of identity come up that he can't turn to you for, and feels that he can't turn to his dad for, because dad is being unreasonable.
Remember, you did what you could to help him by leaving a bad situation. Staying would not have helped. HUGGGGS.