My boyfriend can't stay hard during sex

My boyfriend and I have been together since April 2008. We tried having sex together for our first time in the beginning of August. Neither of us were virgins, but it had been a long time since either of us had sex. He came within 10 seconds the first time we tried. After that we tried 3 or 4 more times and everytime he came within 5 minutes. We tried again about a week later but this time he couldn't stay hard. He said it was because he thinks he cant satisfy me and it makes him go soft. We fought for a long time about this because I didn't really understand it. He never has trouble getting hard, it's just staying hard during sex. I was wondering if this is something all guys experience? I've never experienced this problem in the past.

more......