Sex is a social problem.
Marcuse argues that sexuality is at the origin of the plight of the lower class, because sexuality is reserved for the powerful, and the social understanding is that being successful in the marketplace is a prerequisite for having a fulfilling sexual life. Meanwhile, rich and powerful people are living lavish sexual lives. In other words, what feels like class warfare is actually the pain of sexual frustration in a world designed to repress the working class.
Strict morality is designed to repress sexual instincts.
Marcuse argues that what is commonly understood as "morality" is actually just a complex shame system designed to make people repressed so that they are more dependable workers. This would include religions that shame sexually liberal behavior.
An erotic life is an enjoyable, fulfilling life.
By rejecting the moralism and social pressure against sex, and by adopting a more optimistic view of sexuality, Marcuse argues that people could find fulfillment in the way nature intended, so that they are no longer disillusioned by the false idea that hard work will lead to sex.
