The psychology of the modern young attractive women is pretty simple.
She expects excitement, drama, intoxication, a roller coaster of emotions, mystery. When those experiences have been burned through the spark is gone and it's time to move on unless the man has something else about him that attracts and intrigues her, kind of like a moth drawn to a flame, like listening to Charlie Manson wax and spin webs of irrational cosmic bliss.
Who knows deep down what makes a young women's loins moist, it could be any number of things.
The main point is to be pessimistic and skeptical at all times that you need another person in our life to complete you or even to add any enjoyment at all. That young attractive women you lusted after will one day be old, wrinkled, and whiskered, she will be bitching and riding your ass and you'll curse the day you married her as you drive every day to work wishing you had the courage to drive off that cliff you pass each day.