Don't be so down on yourself..
Maybe you're just going through a difficult time right now.. and you need his support ..

there must be something great about you to have attracted someone like him.
3/4 years is a really long time to be in love with someone, i think.. and see, he didnt give up on you, which must mean he really cares about you..

Dont sell yourself short. you have a lot to offer him, or else he would have moved on, dont u think?