I really wish more of the posts here were written from the "His Needs, Her Needs" angle. I really don't think weight or the OP's husband should have been the focus at all.
Needs are a two way street. A simple way of looking at it from a "needs" point of view:
Doing her best to take care of herself is not just for herself, it also helps her to meet his need to feel attracted to her and helps him meet his need for sex.
Doing his best to take care of himself is not just for himself, it also helps him maintain his fitness so that he can meet her need for home and security by providing for her and their children.
The wife who gains 80 lbs is not doing her best to take care of herself, she is not helping him meet his need to feel attracted to her and is certainly not helping his erection.
The husband who puts on 100 lbs runs the risk of premature heart attack and other negative health impacts, thus impacting his ability to provide for her and their family. Not to mention his inability to control his weight will not make her attracted to him. Women are in general attracted to men who have their act together and a man who gains 100 lbs gives a visible clue that his act isn't entirely there.
Weight gain is controllable for the most part absent serious physical issues that make large weight gain uncontrollable. I expect women my age to be heavier than they were in their 20's; I fully accept that. At the same time, I also desire them to be good with keeping what they have under control. A woman who lets herself go isn't attractive; if she truly loves herself, she will realize that she's not only cheating herself, she's also cheating her husband and her children by placing her health at risk.
However, men or women who undertake weight programs/diets need to be doing it for themselves first. The context being, only by taking care of himself first can one take care of their loved ones.