Sex is deeply connected to themes of both violence and respect and reputation in Thirteen Reasons Why. Unfortunately, it's not well connected with the theme of love. Rumors that Hannah is a "slut" (3.151) put her in a really difficult position in terms of her sexual life. Because of these rumors, she isn't able to naturally experiment with sex at her own pace; plus, her reputation scares guys who might otherwise care about her (such as Clay). When Clay finally does admit his feelings, Hannah's reputation stops her moving forward with him. Not only does her sexual reputation prohibit positive experiences, it also brings on majorly negative ones, opening her up to unwanted, even violent sexual advances from guys who obviously don't care about her (such as Marcus Cooley). Although it may seem obvious, the novel asks us to remember that rumors about somebody's sex life are some of the most hurtful.
The rumors about Hannah's sex life are totally unfounded – they aren't grounded anywhere in reality.
The novel needs to deal better with the issue of rape. Jessica Davis is raped, and then the issue is barely addressed.