Does she feel unattractive or are you becoming unattractive to her?

Some may feel they're getting fatter or wrinklier or whatever. If you still think she's attractive, let her know.

If she keeps commenting on your appearance, maybe time for you to change?

My wife and I are in our mid 40s, married over 10 years and have young kids, and we have sex whenever we get the chance. I buy her lingerie and we roleplay. Sometimes she gets to go to work late and we have sex after sending the kids to school and before she starts work.

I remember an advice from a senior lady colleague over lunch to a bunch of juniors that women liked to hear stuff like they're the most beautiful etc even if they know it's not true. Maybe you can tell her that. Some flirting in the morning before work to create anticipation, flirty messages etc.