I wanted to make a new topic about another question as well. It seems so many young people (18-50) are just not having sex. Men but also women increasingly as well. I couldn't find the exact quote but it's something like "I can't distinguish the Good without sex, food etc.." Why do you think young people are leaving sex behind despite increasing secularization?
I found this very good article about the trend of less sex (in California), which brings up lots of reasons why (and also briefly mentions an increase in depression).
There are other reasons which the article doesn't fully address: perhaps modern sex-education (which likely occurs in California) increases the fear of sexually transmitted diseases...The awareness of disease is so prevalent and the fear of disease is so great that no one wants to risk it. And perhaps there is a higher incidence of sexually transmitted diseases going around.
Also, maybe technology (cellphones/internet) is subduing the mind-body connection so that people are less aware of sensations of the body.
Epicurus didn't know about the bodily chemicals of dopamine and seratonin, but yet he was referring to the good feelings that arise with food, sex, etc. One can only determine for themselves if they don't need sex -- so this is a subjective feeling that is up to each individual. If it is too difficult to find a romantic partner and to do so safely, then one must find other physical enjoyments.