Vanity...depending on the guy, I think your friend is right. Women do it too...not all women, but I know before I was married, there were guys that I thought were 'out of my league' so to speak. I actually ended up dating one or two of them, but it took me a long time to catch on. I had lower self esteem and it wasnt weight. I was thin, but I grew up in a family of overweight people and we didnt have a lot of money. I had glasses on top of that and you know what they said about girls with glasses! I just always thought I was not pretty enough, not cool enough, etc. I didnt realize I was ok until my 20's when guys started hitting on me, some of them hot guys. I would have admired them from afar, but never thought I 'had a chance'. Maybe your beauty and self confidence scare them. Lets face it, some girls are just hot, they know it, and they arent afraid to be b-itches if they dont like what they see. I would be fearful of some girls too if I were a guy. You may have to conciously make yourself more 'approachable'.

Good luck girl...gives new meaning to 'Dont hate me because Im beautiful'. I wish I had such a problem! lol