There are big problems with the issue of how hospitals decide who gets to be with someone who's under their care (privacy, security, and common sense seem to be potentially conflicting priorities), and a lot of them don't have to do with whether or not someone's gay. As this article in the New York Times points out, many older couples don't marry because it would end their social security benefits from their deceased spouse and leave them without income or with substantially reduced income. Heck, if you read the comments, people are denied access to parents, and even legally married heterosexual couples are denied access to each other if their names aren't the same. The solution suggested most often in the comments is to lie. Just say you're the person's spouse or sister or brother...or hell, their third cousin twice removed. Anything that fulfills the hospital's expectations of family is good enough.
But these are two couples working within the legal limits of what's available to them, with legal paperwork appropriately provided to the hospital, and in each case one of them died alone. When people ask me why I'm an advocate for gay marriage, this is often the situation I suggest they consider. And they always tell me "that would never happen."
From your lips to God's ear.