seriously, fvck you.
as a female, you are quite possibly one of the biggest assholes i've ever encountered on this message board. if the ONLY reason you are dumping this girl because she gained some weight, then you are quite possibly one of the most shallow guys on this message board. and that's saying quite a lot.
i hate having to fight over my weight. that people judge me constantly over how skinny or fat i am. and i live in freaking los angeles, the capital of beautiful, and anorexic/bulimic women trying really hard to make it in hollywood.
by the picture you posted, your gf (and she shouldn't be with you, since you are a jerk) is not hurting herself by gaining 15 pounds. you're too busy looking at all the anorexic women with body enhancements to realize that you have an actual person that is comfortable with you. do you know how long people search to find someone that will be comfortable with them?
being 21 is not an excuse. wanting to bang hot chicks is not an excuse. you can probably find a ton of vapid hot chicks that will attend to your beck and call. but they will not stay with you, and you'll find yourself manwhored out, wondering why all women out there have no substance but slamming bodies. you're too busy being concerned about yourself. being in a relationship is also about caring the other person, which you have completely forgotten about.
perhaps i'm bringing out my own insecurities, since i'm not exactly the thinnest person in the world and it hurts me to the very core of my soul that men can be this inconsiderate, shallow and idiotic and i'm thankful that mine cares more about me than how i look. but to expect to live my life 10-15 pounds underweight, worrying everyday that someone will cast a disapproving eye towards me if i order anything more than a glass of water and a salad at a restuarant, is simply unrealistic.
you're too busy looking for others that will agree with you. but note they are agreeing that if you are not attracted to her, then you should not be with her. you're only dumping her because you think she's fat, and NOT because you're not attracted to her. look at yourself. you're the reason why there are eating disorders. why the perception is size zero or nothing. why the entire world is so obsessed with how fast denise richards lost her pregnancy weight or how skinny jessica simpson got for her latest movie role.
she's not your sweet heart. dump her. go for it. she doesn't deserve you, but someone that will appreciate her for the way you are. go ahead and list the other reasons why you don't like her. it will all stem from the fact that you have allowed your brain to rot with the idea "she's fat and i can't handle this. i can't be seen with this. it is so not cool and everyone will just think i only like fat chicks, and if i'm ever seen with her and a hot chick strolls by, she'll never give me the time of day."
impale yourself with a sword. or better yet, just stop posting.