Sometimes what you think you want doesn't turn out as you expect.
There are dozens of examples:
You see a great pair of shoes, try them on and they feel very comfortable in the store. But when you have to wear them for a full day, you realize they are not as comfortable as you thought, and you end up with blisters. And no matter how much you try to break them in, the blisters keep coming every time you wear the shoes.
You see a job posting or ad that seems to be a perfect fit for your skills and career goals. You start the job, then realize the job is nothing like what it appeared to be, and you have to do a lot of work that is either way below your abilities and you are bored, or requires skills you don't have and end up stressed and unhappy. Or your boss and coworkers are first class jerks that are impossible to work with.
You find a particular male/female to be very attractive, charming, and endlessly interesting. Then you get in a relationship with them and realize that the charm is not a 24/7 thing, and the interesting discussions end up being very one sided and on a subject you are not at all interested in - all the time.
Yup, been in every one of those situations myself.
Maybe these are not apples to apples to Ms. DeShields situation, but close enough. Sometimes the fantasy of what you expect ends up being very different in reality.
Who knows what happened. Not my business. Am I curious? Of course. I am human. But in the end, whatever happened that changed her mind about UNC may not make sense to outsiders. It doesn't have to.