o_O;;
It sounds like you "nice guys" are trying to get with the wrong kind of girl. Girls that want relationships aren't the kind of girls that just want a good fuck. Try finding girls who don't put out on the third date...
As far as I can tell, if girl =/= slut, then girl = possible relationship. The girls that are in "relationships" with good-looking assholes aren't the kind that are going to settle down and marry/be with you forever. They're just looking for good times. Try looking for someone who's mature and slightly intelligent.