Am I doing something wrong, if not why do I feel so guilty?

So there is this thing going on with me and a guy. Well first of all he has got a girlfriend and they are dating eachother for a year now. Me and this guy are friends for about 6 years now and about two years ago he loved me. But i broke his heart and i rejected him, but we were still friends. I liked him but not in that way. When he was in love with me he always checked on me and made sure that i was okay, he texted me almost everyday but i wasn't very fond of that. I didn't want him to get his hopes up. And i dont see him that often anymore well yeah. So since about two years when he stopped loving me i kinda started liking him a lot. He changed and i dont even know how to explain it but he changed. It was a good change for him but for me it wasn't. We still text eachother and stuff to make sure how we're doing so there is nothing actually going on between us. And i don't believe in this all "soulmate" stuff but i really do think there is a strong connection between him and me. Sometimes he says that he can't live without me because we got so used to eachother. He already told me that his relationship is not going to last because he doesn't love his girlfriend anymore. And i feel kinda guilty. He asked me questions like, "don't you want a boyfriend?" and stuff. I don't even know how much i like him but i think i like him a lot. So what am i supposed to do? Give up on him? I'm such a mess right now.
Am I doing something wrong, if not why do I feel so guilty?
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