My fiance is 48 years old and under guardianship of her father and is being kept against her will at a nursing home

You need to hire an attorney who does guardianship if you want to contest this.

Venturing a guess, you felt there was no way you would end up with a protective order and so you decided to not engage counsel. If I am mistaken in that belief, my apologies. However, so long as a protective order exists, and indeed, perhaps for quite some time after it ends, you are not going to become her guardian. As far as remaining engaged, the simple fact is it is difficult to be a meaningful fiance when you are prohibited from communicating or being in her presence. That noted, is there another relative who might be inclined to see to become her guardian? That doesn't change you own limitations, but it may be in her best interest all the same.