I'm 20 I've turned down sex a couple of times in college...and the only time I would do it my roomie cock blocked me. BTW it's all up to you but after she fucks you she'll be all clingy and weird and well just become attached to you like "uz her babyz daddeh." TRUST ME they get clingy, well if she doesn't you will and maybe if she's crazy enough she'll threaten to report you to keep you two together (sex = couples sometimes to girls)