Is it possible for a girl to orgasm from penetration when she previously only orgasmed through clitoral stimulation? Meaning, my girlfriend tells me she orgasms after we have sex through penetration, but rubbing her clit only distracts her from orgasming through penetration. Is this at all possible?
The ways people can get sexual stimulation and pleasure run a pretty wide gamut. If your girl says this is what works for her, she'd know way better than the rest of us ever could, so go with that.
The clitoris is the only human organ whose sole function is sexual pleasure. So the brunt of sexual stimulation happens here. Penetration and direct contact are different ways to stimulate the clitoris. Penetration can stimulate other structures like the G-spot, too, which makes for an overall sensation different from direct clitoral stimulation.
The fun is in finding all the different ways to stimulate, and do the ones that work the best (following her suggestions is always a good idea -- communication is key!)
For more info about the clitoris and sexual response, etc, check out these articles: