How can you stop yourself from wanting more?

I have a FWB, we were both hurt from previous relationships, however he was hurt much more than me. At first we were just good friends, we chatted alot, hung out and then he kissed me, we then started to have . As it turns out he was still cut up on his ex and I was beginning to fall for him, so he called it off for my sake. We had a big chat about how we're not ready for a relationship and why he called it off, I said that I was fine with it all and I understood and admitted my feelings. Then we ended up meeting up again, he's made it clear he's not ready for anything coz he's still in love with his ex, so I guess I'm only back with him in the hope that things will change. But we chatted and said that we'll just have fun and see what happens. Although he said that he'd be fine if I met someone else and this hurts me coz I like him and I really cant break it off with him, when he broke it off I was gutted and I was so pleased when we started it again. What shall I do?