I agree. Also, residual shock and trauma, probably. I know people roll their eyes at statements like that but losing someone from your life overnight (and it being their choice) is profoundly distressing and discombobulating. Regardless of how in love they were or weren’t. Especially if the left-behind person has an anxious attachment style (which is extra funsies, am I right?!). It’s quite a primal / biological thing that goes back to being cast out of the pack in ye olden times, when being alone meant a genuine lack of physical safety.I agree but I don't think there could be a person out there who wouldn't have a hurt ego by being so publicly de fiancee, and then worse still have your ex move on to a beautiful good time girl in your own social circle. Wagging tongues etc.
Utterly humiliating.
None of that excuses her behaviour but it might go some way to explaining it. I agree that she’s immensely privileged in every other area of life and needs to find a way (cough therapy cough) to contain her anguish about the breakup and face up to it rather than letting it be her carte blanche to feel endlessly sorry for herself for her entire life situation.