Yes, I would be willing to do that for him. I think plenty of partners had this unspoken agreement of closing an eye to affrairs on both sides as long as the status quo was maintained in their homes.
My aunt, who is now in her 70s, had a guy that was close to her household helping her repair stuff around her house becuase her husband had a disability that didn't allow him develop skills in this area, and that guy remained around her for decades. He is also married. Now my aunt is a widow and he is still close to her. He is and was married the entire time. Everyone of us suspected there was more between them, no one dared to question their relationship, and they stuck together. They even spend holidays and go for trips together (presumably with a group of friends), but we all know they have a special relationship. They always been very decent and never showed that was more between them than a close frienship. Not a hint of sexuality.
Interesting case.