My 25f girlfriend has a thing for her new roommate should we pursue this?

For context she has already fucked my roommate 8 times now. He still has no idea that I know. And that has been really fun.

Primarily because when I am in the house I can hear them together. But if it is all at her house I will have to go over there to hide in order to listen to them.

But he is quite hot and I think that it would be really fun. Apparently one of the other girls in the house saw his cock when he came out of the bathroom and it is big. He is also genuinely really hot. Like if I were a woman I would swoon for him. And want him.

So I can understand why my gf wants him.

What do you guys think?