I stumbled across this posting on Craigslist a while back, about mothers and wives who lose all regard for appearances. While I certainly wouldn't say I agree with all of it, there are some interesting thoughts there.
Many mothers do, in fact, let themselves go as this posting describes, particularly once they pass a certain age and have had two or three kids. I do not, and will never, condone cheating on one's spouse, as this poster sort of seems to. However, I also think that when you enter an agreement with another healthy adult to remain in a monogamous relationship for the rest of both of your lives, you each have a certain responsibility to make sure you remain reasonably attractive to the other person. This is only fair.
I take this responsibility very seriously. I stay in shape. I watch my diet. I get regular manicures and pedicures. I don't go weeks without shaving or tweezing as needed. I wear makeup, perfume, and jewelry. I make sure my hair looks good... even if we're not going anywhere. I wear cute, fitted clothes (again, even around the house I wear cute p.j.s), and good shoes.
When women have kids and begin to completely neglect all of this, it makes me wonder. And when they complain that their marriages are passionless, and their husbands have become detached, I wonder more.
Cause and effect, kids. It's not rocket science. While I certainly hope that we all love our spouses for who they are, the least you can do for someone who's pledged to sleep with only you for the rest of his life is to make it a pleasant experience for him. And vice versa.
This is a lot easier when you're childfree.