It's a poem about a woman of immense potential. She's intelligent (Phi Beta Kappa) and her presence lights up a room.
As her brilliance is recognized, she becomes more sophisticated and traditional.
She gets married, hangs out with the "right" people, talks intelligently about boring topics, buys a house and settles down. She ends up being a lonely widow -- a foil to her younger self.
I wish I had more to say about it, but it's been at least four years since I read it. I can't get it out of my head now though! Can anyone help?