It's only a L because this is something that was obviously on her mind during the marriage
No matter how you try to spin it, if your woman dying wish is to experience better sex than that's a huge indictment of your dikk
It sucks but she was given a shytty hand in life might as well do what you want not follow society’s rules.
She would have had to move on either way because men always leave or cheat on their sick wives there’s been studies where it says the strongest predictor of whether a marriage will last through cancer is if it’s the husband or wife who has it, if it’s the wife, the marriage will more than likely end. Gotta be realistic.