I don't think you were being insecure at all. I would say that you and he are at different stages in your life and want different levels of commitment from your relationships. You want an exclusive relationship where you act as a mature couple. He wants to be with you enough to live with you (I assume) and spend time with you but he still wants to be able to do his single guy thing. You came to understand that he does not want the same thing you do and moved on. Good for you. You cannot change him and are not wasting your time trying to do so. I hope you meet someone soon who is as ready for a commitment as you are and have a long, happy life.