Why doesn't he want to have sex?

I am 16, and my boyfriend and I have been together for nearly a year. We are very close indeed and whenever we kiss he will often feel me up a bit. He always wanted to go further and has sometimes pushed me down onto the floor and even brought out a condom. All other times I've asked him to stop because I haven't felt ready, but two days ago I decided I was - though I didn't tell him. We were kissing as usual and he pushed me onto the sofa and pulled my top off. Then he undid his zip and lay on top of me. I would usually have asked him to stop right then but I didn't and he realised I was ready. He put on a condom and took off his clothes and we were just about to do it, but then he suddenly stood up, got dressed again, and walked out of the house without a word. The next day we talked about it and he apologised profusely, saying he was just so happy I was ready at last. We were soon kissing and down on the floor again, all ready, but exactly the same thing happened. He stood up, got dressed, and walked out. Why? What am I doing wrong? He's always really, REALLY wanted to do it before, and seems so hungry when he feels me up at the beginning. Please, please help, I don't want to lose him. All answers appreciated. Thank you.

he is scared to take your virginity, he is sacared himself, there are various possibilities, he could be hidding something.

He might be jst teasing u. Becoz u hav stoped him many times so he doing it to u.or he might be feeling that u are ready only becoz he wants to hav sex. Well its not that big thing u should talk to him and tell him beside sex u enjoy being with him.and when he wants to hv sex for sure you will be there.jst hav a heart to heart talk.there are other things beside sex in a relationship

Could it be that he is worried that he can't get an erection? It can be a self-fulfilling prophecy. If he gets it into his head that he might not be able to get hard - he won't. The answer is for you to help him. Don't just lie there, play with him. Make it fun, not serious. Take your time.

Thank you, we have talked more and he was feeling guilty because he thought he'd pushed me too far... But we're fine now and we're just taking our time with the sex issue.