Kelly was...(spoilers)
In my opinion, dead or at the very least, without a leg and possibly more.
He imagined she was still alive and healthy, and could never admit she was gone.
He even dreamed of her with an amputated leg.
And think about this......
He never...EVER...sees her again as far as the movie goes along...every time he SEES her at the rink of elsewhere...she is always wearing THE SAME THING...she is a ghost.
that is my take...he is delusional in seeing her.
She is either dead or severely crippled and would never want to see him again.