
MC, who has a deep-rooted insecurity, struggles with finding happiness in other aspects of life aside from sex. He's implied as a virgin and maybe he perceived sex as the highest form of pleasure in life, hence why he wants to acquire it. He apparently has a loving sister but does not give attention to it. Perhaps in his struggle in loving himself makes it hard to see how other people love him.
wow, all of these charac designs for people who won't even appear much and not in the domain of possible love interest for MC(╯°□°)╯︵ ┻━┻