Could there be something else going on?

Sounds to me like he's not over his ex. He seems to want to have someone in his life that cares, but doesn't want to get too involved. Might be a trust thing since the ex cheated on him. He needs time to heal. Wish him well, but don't get mixed up in his emotional stuff. Move on with your life. You sound like a wonderful, caring person. Give yourself some time also and you will find someone that deserves you. Good luck.