You can love someone and still not accept the things they do or who they have become. A relationship is nothing but a long term compromise. They rarely work out happily when one person is a selfish prick and the other does all the giving. My advice is compromise on the iasue. Lose about half the weight and keep with the therapy. She cannot expect him to do erything to make it work out while she does not concede some things. It will most likely lead to a bad end. He will eventually stop trying. Their relationship might turn hostle and one or both may end up having an affair. Leading to a bitter devorce. Also physical attraction is a major part of a relationship. Turning to drugs just so that he can physically preform (granted there is no underlying medical condition causing the lack of sex drive) is not a smart move and should be advised against by his doctor.

I was in a similar situation but on her side. Though i gained weight from different reasons. Drastic change in lifestyle. I worked construction for years. Eventually got an office job. The pounds piled on faster then i realised. It evetually caused strain in my relationship. Like one commenter said just making the effort made my marriage considerably better. I am not a hundred and forty pounds again but i do make the effort.