What do you think about me revealing a secret to my friend that his girlfriend is keeping from him?
That's generally not a good idea. Is this about the behavior you told me she was presenting?
Yeah but I can't tell you much about it.
It's nice you want to look out for your friend, but revealing secrets is a private thing. I wouldn't get involved.
I really just want my friend to feel better if this secret is related to her bad behavior.
I get you're trying to help your friend, but like I said, let them work it out.