The other night my grilfriend and I had sex for a half hour or longer and she had multi-orgasms and she then went into the bathroom masterbated. What is wrong with this?
First, there's nothing wrong with masturbation - even if you're in a sexually active relationship.
Your girlfriend masturbating right after sex is something that I can understand you feeling uncomfortable about. Perhaps she needed one final, bigger orgasm to feel satisfied - as strings of orgasms might leave her wanting more.
Try talking to her about this issue. Perhaps next time you can use your fingers (if you've finished with sex) if your girlfriend is still feeling excited. This allows you to remain part of the process rather than her going into the other room and doing it herself.
Let her know you want to please her, and ask how you can best do that. Chances are she'll be thrilled to include you.
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