Why does he like to pick fights?

Im new to 7cups and I really need help on a certain topic. My boyfriend and I have been best friends for years and recently got together a few months ago. Things have been working out great until recently. He has started getting mad at me for no reason out of the blue. When I ask him about it, he denies he was ever mad and blames me for the situation. I know that he has been stressed with something lately but Im really confused as to why he continues to do this and why he doesnt see how hes treating me. Is there any specific reason as to why hes doing this? Does he not want to be with me anymore? Should I break up with him or continue to try to fix things?