Again, I'm fairly laid back when it comes to my hosting. Letting someone stay at my house an extra day for any reason would't be a big deal. But, I also read these boards and have discovered that for many, hosting is huge huge deal to them and every aspect of having a guest is carefully calculated. So, having someone stay even one extra day can be a big inconvenience and stressor for them.
That being said, crap happens. People get sick. Flights get canceled. Storms rolled in. It happens. And yes, it's pretty darn cruel to throw someone in pain out of your house.
But, I think we are spending too much time focusing on the emotion of having a disabled person in pain kicked out and not on the etiquette of the situation. The GF knows that she has an issue. She knows that things that she sometimes can't control, dibilitates her to the point she can't move. She agreed to accept someone else's hospitality and stay in their home (it doesn't matter what the original motivation for inviting her was). She also knows that there is a chance that her disability could mean that she needs additional or special accommodations. Yet, she still thought it was an intrusion of her privacy to have to explain her disability. It doesn't matter that she answered questions...if they had not been asked, she would not have disclosed the information...yet, when she needs extra accommodation her host is supposed to provide it no questions asked. It's hypocritical. If you know ahead of time that there's a chance that you are going to need more than what was originally offered, I think the only polite thing to do is forewarn your hosts.
Here are the contradictory arguments I heard that I have a problem with: (paraphrasing).
"I don't like to be seen as a burden, so I try to act as normal as I can and do things that risk hurting me more. Yet, I don't understand why people are treating me like I'm normal and expect that when I do things that hurt me, I shouldn't be hurt."
"I think it's intrusive to ask me questions about my disability. When I need something, I'll tell you. I expect you to provide me what I need, but I shouldn't have to explain any of it to you ahead of time."
"I know that I can walk some distance. I also know that at some point I'll probably have to stop and rest. Since I don't know what that distance is and because it's different every time, I don't understand why I need to say anything to you before hand. When we're walking together and I suddenly can't go anymore, I expect you to completely understand why."
I get that the GF answered the mom's questions about the disability and volunteered some more information...despite how intrusive that felt. I am still not putting blame on the parents. Not because I think the GF should have said more (it's not what she said but the attitude/expectation she came with that I don't like), but because the person that communicated the need to stay one more night didn't even understand the severity of the situation. If the person asking the question doesn't even know that she's in too much pain to walk, how in the world do you expect that the parents are going to get it? It makes absolutely no sense to blame them when it's almost impossible that they had a clue how bad her situation was.