Confused by a man

I have been sleeping with a man for the last 6 months. We hang out together every single day. But there are a lot of confusions to this "relationship." He and I always talk about how we don't want a relationship. But I recently decided that I am in love with him. I know I'm the only girl in his life, but sometimes when we go out he will hit on other women in front of me. There are nights when he and I yell and fight (he is never physically abusive.) but when it's good it's so good. We talk about everything and laugh and he tells me he loves me. He is my best friend. What should I do? Is it worth it? Help :( I have no one to talk to about this...