Why does it bug me so much when my girlfriend gets wasted?

you just care about her and your scared she might go over board. Its okay to be worried for her it means you care.

I don't think you are being controlling or irrational. This must be a problem, because you are not mad she's getting wasted, your worried. I'm guessing she probably gets wasted too often, or just doesn't know how to limit her alcohol intake? Well you should talk to her about it, in the end she will decide what she does with her body, but just show your concern without it turning into a big blowout!

It's not a good look when you're sober, is it? You look much the same when you're drunk. If she does it often when you're sober or not around, you have a point. If not, you're being irrational.

Because if she is out drunk alone people could take advantage of her and there is ALWAYS the possibility of cheating & also when your sober it's really hard to talk to drunken people there completely different people .

controlling and irrational

fear that she is going to get laid or raped

also because you know that in that condition, you can/should/would rape or lay another girl