What is a non-negotiable factor that would prevent you from engaging in sex with someone, no matter their attractiveness?

A fundamental dealbreaker for engaging in sex with someone, regardless of their attractiveness, is the lack of consent. Consent should be clear, ongoing, and enthusiastic from all parties involved. Without mutual consent, any sexual activity should not proceed as it violates personal boundaries and autonomy, thus being an absolute contraindication. Additionally, issues such as dishonesty about important facts like sexually transmitted infections, or disregarding established boundaries and safe practices, also serve as critical dealbreakers. These factors ensure that the encounter is both safe and respectful, adhering to the values of dignity and personal safety for everyone involved.