Why would someone act this way?

I have broken up with and gotten back together 5 times with my boyfriend thanks to his insistance and chase and begging which eventually has made me go back to him for the sixth time.

I have told him I don't like him, I have told him I don't love him. I have told him I don't see a future with him. I even told him it was not a serious relationship for me. Yet, he wants to stay with me and get engaged with me. Everyday he asks me to meet each other's families and make our relationship official despite me saying that I don't want such a thing.

Everytime we broke up, he would start to come around my neighbourhood, and even chase after me. He would even come near my house to ask me to get back together. I always refused, and even told him not to come around anymore. But he wouldn't stop. He would insist until I would change my mind again. Only to break up with him again after some time.

I mean, what's wrong with him? He says he can't forget about me and loves me. I feel like he doesn't care how I feel about him as long as I stay in a relationship with him. Why he acts like this?
Why would someone act this way?
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