?Sorry to say but that's a major red flag. It's one thing if she said she thinks it would be weird but was ok with it. But it's a whole other thing if she got upset. That implies she's trying to keep things with you and her separate from her and this guy
Tahe this Guy friend with you to work one night and push his ass into a grave. Then start burying him till he spills it all.
I just think she doesn't want you to interfere in her friendship, just like you wouldn't want someone to burst into your relationship. Or she's cheating.
No doubt shes cheating i believe its bc of your late working hours so this guy is her new way of getting the romantic sexual pleasure she seeks i mean she only sees him when ur gone for a reason
Sounds odd she gets mad at you suggesting you come with them So my guess is she feels your not giveing her enough attention so this new guy gives her all the attention and sexual pleasure. They RED FLAG
Maybe she's not wanting you to go to the club with them because she doesn't feel like she can be herself and dance with whoever. Or maybe she feels like you might be a bit clingy if you went. It doesn't necessarily mean that she's cheating. And her sleeping at his place and vice versa doesn't mean anything... For all you know her guy friend might be a closet gay dude... And she accompanies him to gay clubs... I don't know if you should be asking for advice in a forum where most people are extremely negative and immature. This is your relationship that you are talking about. You have guys telling you to beat her because she's definitely cheating. If you don't trust her... Then leave her alone... Simple as that.