Going back to what I was telling you about my Mother. We honored her wishes. They were in writing and she was terminal. However, if my stepfather was the only one saying that she wanted no extraordinary means of preserving her life, while he had a tootsie on the side with whom he had had 2 illegitimate and was the sole heir to her estate, you can bet I would have interfered in the marriage vow. As it was my stepfather was completely faithful to her, took wonderful care of her and tried harder than any of us to get her to take treatment. A marriage vow between a faithless husband and a helpless wife does not deserve the respect you are demanding.
Scenario A: She pulls the tube, five years later she meets someone new and starts a new family.
Scenario B: The courts don't let her pull the tube. My body stays alive for decades. Now when she meets someone new five years later it is called adultery. But I don't want my wife to put her life on hold for decades while she fights a legal battle.