EDIT: I don't want to break up with her for no reason at all, unless she cheats on me and I don't think she will, but you said that sooner or later she will, so yeah, I might as well let her do it and see how it goes, if she then wants to break up with me, so be it

My girlfriends told me she wants to try to have sex with a man, and I was surprised obviously. She said she still loves me, and I love her as well, so I don't want to break up with her, but I don't want her to do it because I'd make me uncomfortable, but I also don't want to stop her from something she wants to do.

Of course I already told her that, and she understands and she also said she knew I wouldn't let her do this, and it hurt, I feel like I'm doing something wrong, and I probably am, I just want her to be happy.

And we've been using a strapon for a long time, so it's not much more that I can do to satisfy her desire.

I really don't know what to do, I need some advice please.