I used to think it mattered but I ended up realizing how superficial it really is and it made me much more comfortable about myself. I may have had a sexual relationship with a girl that had been with a bigger guy but it doesn't matter to me, the fact that she likes mine is what is important. I try not to get obsessed over comparing myself to other guys, but when I do I make sure it doesn't bother me. It's just not important enough to bother me.