help me x

I have been on and off with this boy for a year. When we see each other it's great but we've also spent large amounts of time apart. He will message me wanting to rekindle what we've had and then I see him, we have sex and then all of a sudden he goes into moods which I react badly too and it's back to start when we don't speak. But sometimes we do get on for a good while without arguments but just lately we haven't spoke because of them. But I don't want to let him go because I enjoy the sex and I have feelings for him as person, but I'm starting to understand he doesn't have as strong as I do. Help!