So yeah, was sleeping with this girl in my "close social circle", we aren't exclusive or anything, and its been like a month since I last hooked up with her, but she tells me a few weeks ago she slept with one of close guy mates at uni.

Do I owe it to myself not to sleep with her and just move on?

What's your objective? To fuck her or date her?

I'm assuming you'll just want to fuck her, because dirty bitches like that aren't to be dated. If you want to fuck her, then no, you don't "need" to move on. Keep in mind you weren't even dating her, or weren't her exclusive fuck buddy. So she owed you nothing.

By the way, why is it you haven't fucked her in a month? Her fault or yours? If it's yours for not making any advances, this could be her way of telling you "when are you gonna fuck me next, you asshole?" But personally I would just stay away from that filth. Naw mean?

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Before she can respect you, you need to respect yourself.