@Catcakes, my daughter dislocated both knees, three months apart. The treatment was physio excercises, however her first knee wasn’t recovering. It turns out that our family are hyper-mobile, meaning we have very elastic ligaments, and without wearing a knee brace to keep her knee properly aligned, the constant misalignment of her knee joint meant it couldn’t repair.
This was the exact opposite of the usual treatment, which says that the knee joint won’t regain its strength if you wear a brace. It caused a lot of confusion.
There are ways of testing for hyper-mobility to see if this might be the issue with your partner. My D3’s second knee gave out over having to bear the strain of such a lengthy recovery of her first knee .... but it was all tied into even looser ligaments during teenage growth spurts .... she went from elastic to not being able to hold together.
but I know that feeling well so laying down for the afternoon sounds like a great idea @Faith-and-Hope I have a feeling I will be doing a lot of that too today. I can't shake this headache today (even with stronger painkillers) - lack of sleep and crying this morning has certainly not helped. Just a day to get through today and see what tomorrow brings (for both of us) 
