From long covid? And because they didn't go two years without standing? You can't really believe this. Going outside would not kill her. Choosing to stay in bed for two years has done her far more damage. Staying in bed is worse for you than hard drugs.
Unless you got cold fever and you're literally too frozen to get outside, or you got your leg broken, there is absolutely no way you wouldn't get out at the very least once a day.
I believe it's a mix of depression and lack of will, being hungry and having nothing to eat is the best way to make someone get back on his feet. It happens everyday with the lower class, but people in the top of society don't feel that very often, or even at all.