GF Gave In To Roommate

So me and my GF have been together a few years. We work and both make good money so we took on a roommate in the spare bedroom, a lazy 20yr old kid that would cook and do chores. Long story short we’re all having drinks, she is getting horny he is getting confidant a hand grabs her ass. I knew it was gonna happen I didn’t stop it. I got my girlfriend back sloppy, sore asshole, big smile.
I took her back rough and she loved it