Thank you for your email and the courage to ask your question. The best answer I can give you is two pronged. First there is some support for the idea from an evolutionary perspective from something known as transactional sex. This means that the use of sex to obtain food, shelter and safety may have some evolutionary survival roots. More psychologically and literarily, particularly since you say: “Seduce the antagonist” you may simply be anticipating the arc of the story. Consider this article about female roles in literature. It highlights how female characters from Shakespeare through Disney have used their sexuality to manipulate outcomes.
Since these are thoughts triggered from tales you are reading or watching than from your personal life I would guess this is more about your literary sensitivities.