I am not a caretaker but a survivor. The largest amount of recovery is in the first 6 months, After that it takes a lot of work with the survivor needing to have good cognition in order to understand and help the recovery. The dr. who said that a second stroke will always follow should not be talking like that. He should have given you information on what has been done to prevent a second stroke, clot, either Warfarin or aspirin, bleed, clipping or some other surgery. Is your fiance actively working to get recovery back or is he depending on you? Stroke recovery is a lot of hard work. I am 52 and it basically takes all my energy, both mental and physical, to work on my recovery. I can see why those in their later years just give up on recovery and just live with what they are now. Only your fiance can determine if he is willing to recover more than he has now, you as caretaker can only do so much.
Sorry about no clear answer.