Since you are a poet, I hope you will not be offended if I focus a bit on the nuances of the way you tell your story. You speak of "this person I have come to know, like, and admire so much." You say "I'm quite lucky to have someone like her. She is a rarity." You say "she is quite precious to me." I don't think this is the "poetry" of love. (Is it?)
Given what you say about your friend's serious medical condition, is it possible what you're feeling is deep friendship, concern, commitment, all very good things, but not exactly love? Maybe some clarity about your feelings would help you make the decision.
I'm not saying it would be simple, even with that clarification, but at least it would be a start. My gut feeling is that a great scholarship is not to be turned down, and both love and friendship can continue at a distance. But there's nothing irrational about putting your friend first, if that's what you think is best. I'd just make sure I moved forward in a clear-eyed way.
If you do decide to transfer, hopefully you can still be helpful, just as you are right now, from a distance of 1000 miles. Whatever you decide, this sounds difficult, and I wish you both the best.