I’ve been in a similar situation where my bi gf told me that she missed dick all the time, said that what we did was not the same, and that bi people can never be faithful because nothing is ever going to match up to dick or boobs so they were going to cheat either way.

However I think you’re focusing on the wrong thing. It’s not her sexuality but her behaviour. Literally every single person I’ve dated since that gf has been bi (four others) and I’ve never ever had a similar problem come up again. If you don’t like how she’s acting, that’s totally understandable but I don’t think it has anything to do with being bi or not. If she was saying that she misses all the pussy she was getting before you became exclusive (if you are exclusive), and that pussy was way better than yours for whatever reason, that would be incredibly rude as well and you’d be justified in dumping her for that.

Not trying to “scream” at you but just wanting to say that I see you and feel for you but also don’t completely agree with you at the same time. Let’s not turn this into a gate keeping queer community thing when you have more of a problem with the behaviour than her sexuality.