Most Helpful Guy
Lots of 'em do yeah. It's because it's more of a status thing in highschool. They love to brag to their friends about how hot their girlfriend is, and are afraid that they'll get made fun of if their girl isn't considered attractive by most. Not all hope is lost for you though. Eventually you'll get a boyfriend who thinks you are pretty. Also depends a bit on how picky you are with guys.
Most Helpful Girl
Not all guys do. In HS there were some who dated girls who wouldn't be considered on an equal level looks wise, but their personality was probably what made the difference to the guys. Goes both ways, if you really look around you'll begin noticing girls dating guys that make you wonder what she was thinking... yet those guys are really likeable and comfortable in theirselves. So you don't have to be the head cheerleader to get guys to like you.