Is In It Yet?

I've only been dating this girl for a couple months. I knew while I was at class she'd been sleeping at my apartment during the day. It all struck me as odd however, when I found a used condom in the trash...

My computer is in my bedroom so it wasn't hard to set up my webcam to record all day. On day two of recording she shows up with some random guy. They climb under the blanks of my bed and and start fucking.

On the cam my girls head is kinda hanging off the bed and she looks board as fuck while he's fucking her. The guy asks "what's wrong" and my girl says "Is it in yet?" while laughing. He gets pissed and tries to get off her but she holds on and ends up flipping around and starts ridding him all while saying she was kidding.

Anyways, I get about 10 minutes of video of her ridding him hard and then she gets in the shower.

I don't know why she's cheating but it doesn't look like it's for the sex.