Honestly, evolutionarily, men in their 40s are probably the prime age for women to be attracted to. (1) They've proven who they are, their character. As a woman, you can see his life and know whether he will provide, protect, and parent or not. You also know whether he will take care of himself well, in terms of health and physical fitness. (2) Most mental illnesses and other genetic problems would have already manifested. (3) Sperm banks accept donor sperm up until age 39, so a man in his 40s is just past that so still got pretty good sperm. (4) If he's made into his 40s and is still obviously of good quality, then he'll probably live into his 70s and 80s, long enough to see his new children into adulthood.