It's probably because ugly people stop caring about who other people are snogging and don't stalk other people to try and find pointless correlations between attractiveness and lengths of relationships. Us people with either low self esteem or "boring" lives like to focus on things that matter more than sex or girlfriends.
I know, it seems counterintuitive at first, but once you get the hang of it, it's rather pleasant. You also tend to focus more on work and unequivocal jibes at your substandard sex life go through one ear and out the other, which causes people around you who are trapped in the vicious net of "OMG I DONT HAVE A GF" to start idolising you, and eventually to begin fancying you (as age increases and immaturity decreases).
In conclusion, <insert cliché about being oneself or some other Disney movie line here>. (Personally, I like the one with Mufasa appearing as a vision in the stars to Simba in LK1, but you may take your pick).