Fat or skinny-doesn't really matter,all you need to do is look at the average married 40 yr old woman. Never having another woman? May actually act in his benefit- after you are used to watching a different movie every week, are you going to want to watch the same one for the rest of your life?[my kids did when they were little] Ignoraance is bliss. He won't be comparing every sexual act with every girlfriend/FB he's ever had.
The real issues are: is she a quality woman[other than looks]?,Is he going to be happy never having had another woman? You can ask him,but then you'll have to let him do it.