Two thoughts based on my experience.
Performance anxiety-men of a certain age+alcoholism=difficulty performing.
My AH seemed so embarrassed and upset that he could not "please me". Well for me it was more about the emotional intimacy that seemed to be lacking elsewhere than the actual physical act but it is different for most men.
Manipulation. He wanted out but did not want to say it for a long time. His heart wasn't into the marriage but didn't want to be the first to walk away. I believe he withheld his affection in order to manipulate me into making the first move. We went from not having sex, to him sleeping on top of the covers to him sleeping on the couch. When we finally agreed to separating and I found a place to go first he said "Now I can sleep in my own bed". Mind you I never asked him not to sleep in our bed and there were other beds in the house. Typical "whoa is me, I'm the victim" mind games he plays.
It is not you! I played that tape in my head for a long time. Congrats on losing the weight. If you feel you look good, and I'm sure you receive compliments from others, don't let 1 person's lack of attention make you doubt the beautiful person you are!