What can I do to change his mind?

I like one guy. We became friends and we see each other among mutual friends like every two weeks. He is single. But he liked one girl and things were looking good for them. I already thought they are together but then she ended things. It really hurt him at least what i heard. It happened like 15 months ago. He is nice, funny, cool and he always smiles. But when someone mentions dating in front of him he just laughs. He says thinks like why would he do it to himself again, the girl will find someone better anyway and that he likes himself so he won’t date again. He protects himself a lot and he doesn't trust anyone much except of his closest friends. I guess he needs time maybe but what to do to change his mind.

What can I do to change his mind?
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