What should I do if I don't like my boyfriend anymore?
What caused you to not like your boyfriend anymore?
There's something about him I don't like the way he reacts to me
If you feel you are not into your boyfriend anymore then it is ok to move on. Not every boyfriend you have will be one you stay with. It is important to understand why you dont want to be with this boy however, so you learn from it down the line.
I have no fucking clue why I don't like him so much anymore.
It's important to spend some quality time with your boyfriend so that you can understand your feelings about him better. If you are sure about not liking him anymore, it would be appropriate to respectfully end the relationship.