why is it that i can not finish when me and my girlfriend have sex?!

Best Answer - Chosen by Voters

You should try different positions, speeds, and motions, until you find what works for you. You have only had sex three times so you can't be expected to be a pro at it yet. Talk to your gf and tell each other what feels better and what does not. Try different types of condoms as well, there are so many types that claim to work better for men or women so just experiment until you find what works for the both of you.

You either using alcohol or drugs during sex,thereafter you are using a lot of energy to reach your climax and final you don't succeed the whole process,but she may end up ejaculate couple of shorts than you but your the one who don't finish the whole process,try to do it when neither of you is drunk nor druged.