'Mind if I watch'?
Well...Why not, right? I actually kind of expected her so join in partway, or at least start masturbating or something...I mean she even stripped halfway (and her friend even called her out on it).
Great ending though. Hah, well, at least everyone's honest with each other. Calling her out on stripping and saying she won't get a boyfriend if she does stuff like that, and her returning it with sarcasm...And him just being interested in his girlfriend's friend's panties despite already having said girlfriend.
Update: Why didn't we get a threesome!?