what can i do if a guy keeps going back and forth between being committed/non committed?

ive been dating a man who just got out of a long term relationship when i met him. he told me from the start he couldnt commit to anything serious. I was fine with that too. I then wanted more, he agreed. then i found out he was seeing someone else. we eneded it and then started up again. then there was an period of time where nothing was talked about. Then he came to me and said he had all these deep feelings and wanted us to go to therapy. we ended the talk because the timing was really bad. i chose not to bring it up again but then realized he was still seeing other women and everything started to unravel. until i blew it. he honestly tried very hard to make things work for both of us but i didnt walk when i wasnt ok with him seeing other women. now he wants nothing to do with me and its my fault. can i do anything to prove im sorry?