Jim0987 #6 - starting a bit of a rebuild

[Mozza]

I think your last analysis is spot on and you should just have asked no questions, not even "Had a good night out?" You need to act like she doesn't matter. She gets a kick out of being the object of your attention. She'll be puzzled when she thinks you don't care much about what she does because you have other stuff going. None of us think we're all that interesting, until someone else starts looking at us with admiration or envy.

By the way, you seem to assume she's getting a lot of action from OM, based on little actual evidence. I suggest you dial it down for your own good and to be closer to the truth.