This point of view is so alien to me, that it's difficult for me to put myself in another person's shoes to imagine it because sex is pervasive.
The drive seems to underlay so many other human endeavors seemingly having nothing to do with sex.
The teacher crush, the teenage wet dream, the furtively and pathetically trying to impress someone, the awkward first date - these are all milestones of growing up in our culture.
The character involved ends up living much of his early life in a monastery, so he's not in a cultural setting where he is pressured to have sex - although there is some homosexual activity going on around him. However, when he does experience attraction (to a woman; and well into adulthood) I'm sure it really took him by surprise and he wasn't prepared for the other feelings it would stir up.