Depending on your physical and mental conditions, a man's libido and desire is as much or more when he is over 40 than when he is younger.
A guy over 40 may be divorced, or a widower, or just a single who is still looking.
A lot of guys in this situation find women close to their own age, but some (and more now with the advent of the "sex potential pills") are looking for girls in their 20s.
The internet has made this kind of a search easy, and a lot of relationships, and...