Note: Due to early aged abuse and continued use of alcohol or other substances; the females brain will never reached a mature adult level and she will consider herself still young.
degenerate - Having fallen to an inferior or undesirable state, especially in mental or moral qualities.
deviant - deviating, as from what is considered acceptable behavior
deviate - To depart, as from a norm, purpose, or subject; stray.
pervert - a person whose behavior deviates from what is acceptable especially in sexual behavior
Another reason is there is no kissing to make it all personal, there is no I love you's to set up for a future disappointment and last but least the younger man always leaves so that the ladies can go on with their daily business. Nothing is ever said, it's always discreet and that makes the sex even more great!
A plus side also is that younger men are so much more sexier these days!
Meaning Her mom is looking for some fun with a younger guy.