I would suggest that relationship counselling would be helpful for you both to discuss how this situation is affecting your relationship and your feelings for each other. Having a third person to help mentor the discussion is a helpful way of safely and honestly airing your position as well as helping both of you to understand each other's needs at the moment. Divorce is the last option, and is best only considered once all other options have been tried. As you mention, you feel you have already ruled out the relationship counselling as an option, however you might consider asking whether you could come along to one of her counselling sessions, to better understand what is going on for her at the moment. It is possible this has been triggered, consciously or unconsciously by her being back home and visiting family, and it is possible there are underlying events, traumas, or feelings that are unresolved for her, that she is coping with through this health condition. I would be very open to the possibility that for her there is likely more to this, and if that is the case, an open mind, suspension of judgement, and a lot of support is what is required until she works through this. It is good that she is going to counselling, and if this is of quality, she should gain the help she requires to work through the crisis she is in at the moment.
Alongside this, have you considered getting a similar type of support yourself. It is possible to attend relationship counselling alone, and this would help you to discuss your frustrations at the moment, and to perhaps find a different perspective on the situation and on what is going on for your wife. Love is unconditional, and reading over your initial question, I would consider whether you are perhaps putting superficial conditions on your love for her at the moment, and whether she is sensing or feeling this in a way that might actually be exacerbating the crisis she is going through at the moment. There is much research at the moment regarding the relationship between our physical health and our emotions, experiences, and memories, and how unresolved emotion or trauma can actually manifest as physical symptoms, if it is being repressed or ignored on the emotional level, so keeping an open mind about whatever is going on for your wife at the moment might prove beneficial in the long run.