All of these abilities stem from the neocortex, the latest part of the brain to evolve. The neocortex gives us the ability to give meaning to life. As such, the more meanings we give to sex the more rich is our life - increasing our ability to feel good. Intimacy is a major aspect of love and is explored by Bottone and Sipe in A Triangular Theory of Love . These authors include intimacy as the emotional component of love.
Intimacy is able to boost self-esteem and add meaning to life.
Whereas, most human beings feel depressed and lonely when they are isolated from other humans. Yet, fear of rejection keeps many people from developing an intimate relationship. Some will avoid contact at all, while others will present a false front or an illusion of themselves. Some people have a trouble balancing closeness with the preservation of individual identity. Genuine intimacy involves disclosing oneself and trusting one's partner to accept him or her as he or she really is.