<human>: Can you condense the text into a few key points?

My boyfriend and I (I'm a lady) have been together for about a year, and we're both 19 and sophomores in college.  It's been a wonderful year, and when things are good they are so amazing, we love each other more than anything.  We became fast best friends last year, and that developed into a strong relationship where we pretty much spend all of our time together and both greatly enjoy the company of the other for 18+ hours/day.  We both have small anxiety issues and in the past when a problem arises it's usually from a misunderstanding, but we talk about it and then everything is fine again.  However usually he won't tell me upfront there's a problem, just act distant and upset until I confront him.

He's had rough past relationships, and we were both extremely grateful/surprised to find each other in college.  Usually we're incredibly happy together, but recently him telling me "I'm sorry I'm wasting your time/Do you actually still want to be with me?" has become a lot more frequent (from about once every four months to every two weeks).  Whenever he gets this way it rips my heart out, and its increasing frequency is making it harder and harder to deal with.  After I become upset over feeling like I'm not enough for him, he just apologizes and retreats further inside himself.  

I don't know what triggers him being upset, it can come after I disagree with him on a political point, and it can come after me kissing him.  Sometimes he says he thinks I'm only with him because I don't want to hurt his feelings.

I love him more than life but I don't know what to do to help.
<bot>: Boyfriend's low self-esteem makes him think he's "bothering" me, and he won't confront me directly about something that's bothering him.