The DM is a load of rubbish, but this article does have a valid point.
It's really easy to get to a point where neither of you are trying and that isn't particularly sexy for either party which isn't great for the marriage. Men do it too tbh with putting on weight.
Not saying you need to do it every night, or that just the wife needs to do it but a bit of effort some of the time is a good thing.
A woman’s appearance is the most effective weapon in her arsenal — her brains and personality count too, of course, but looks matter more to men, no matter what they might claim.