Most Helpful Guy
Long distance relationships usually are more trouble than they are worth, based on what I've seen. (I've never been in one myself because I think it is a terrible idea). I'm guessing that the two of you have great sex together and he doesn't want to miss out on that but the relationship is too complicated.
Most Helpful Girl
He just wants sex. Doesn't that seem straight to the point? He broke up. Then wanted to be just friends, then thought being friends with benefits sounded like a better idea to him.
I assume he was your boyfriend? Then things weren't working out on his side and he felt like being friends with benefits was a better option.