I'm thinking maybe you can say that you didn't really say what you meant. It's not true that you don't find her attractive. You do find her attractive. The proof is the children and your desire for her both as a wife and a lover. But you think that she could make herself more attractive by taking care of herself. I'm thinking of the before and after pictures of women who got makeovers in the women's magazines. They weren't unattractive before, but going to the hair stylist, and the make up artist, and putting on designer clothes made the most of their beauty. And then the magazine takes a picture and puts it next to the "before" picture, and everyone says "Wow!" You think she could enhance her beauty by doing those things.
I, as a woman, would not be insulted by that. Anyone else have any thoughts?