This has been covered extensively by the major advice columnists, including the likes of Ann Landers and not just Dan Savage.
Loss of sex drive and/or physical intimacy happens to both women and men, and I’m not convinced to one more than the other. I’m not even sure I agree with your premise that there are more old guys than old women prowling here, and in any event I wouldn’t expect the population here to be symmetrical even if men and women lost interest in similar proportions
Women, for their part, go through lots of hormonal changes in middle age that either impact their sex drive, or even if their drive isn’t reduced, can result in reduced physical receptiveness that can make sex more difficult and/or embarrassing.
Men, meanwhile, also often have more challenges getting (or maintaining) erections for a wide variety of medical reasons, some of which can be counteracted by the little pill and some of which cannot.
Then there can be a whole lot of psychological and relationship reasons behind a drop in sex drive and intimacy too.
Sorry, there are no guarantees in life. If you started this thread in hopes of reassurance that you’ll keep happily fucking until the day you die, or looking for simple solutions, you may not find them. Enjoy each day and each fuck to the fullest.