My dad wasn't technically in a coma, but for 5 years he couldn't eat, stand, talk or do anything for himself after a major stroke. Shortly after the stroke the hospital gave my mom the choice; with no way to know if he will ever get better you can have him tube fed and see what happens or you can let him go, basically starve him to death. She couldn't let him go.
Once established that he wouldn't improve she couldn't find it in her to pull his feeding tube. She visited him every day. Meanwhile, because there was no quality of life, all of us were hoping he would pass on. Yet 5 years later when he did we still weren't emotionally ready for it.
That was a harsh choice. What a tough decision either way. What spouse would starve their spouse to death.
I hope I never become a burden like that to anyone.