The girl has to just say no and set boundaries! Teenage boys seem like they are always horny, just set ‘em straight and say no!
Perhaps some boys think this, but assuming all boys think this just isn’t true. Boys and girls should be respectful of their partner’s wishes, not just about sex, but about all things. Some boys may learn strategies to make it easier for them to convince a girl to have sex.
However, healthy relationships are characterized by clear communication, including discussions about safe sex and boundaries, and mutual respect for one another, including not taking advantage of one another in emotionally vulnerable moments.