Is it normal i dont care about my gf and my roommate?

My roommate is a pretty nerdy and weird guy not to mention a virgin. When hes not at work he just sits around in his underwear all day and plays on his computer. Few weeks ago he went up to my girlfriend and asked if she would let him fuck her in the ass. My girl jokingly said she would for a million dollars and he got the hint and that was the end of that I thought.
I woke up a few days ago to find my girls underwear with cum stains and smelling like vaseline. On top of that they wont even look each other in the eye anymore. Turns out he's been begging her nonstop for the last month and she pretty much caved in. Here is the thing, honestly I don't care, in fact I find it funny. What do you guys think?