(a) In any prosecution for an offense under this part based on the victim's being mentally incapacitated, physically helpless or impaired because of mental disability or disease, it shall be an affirmative defense that the actor, at the time such actor engaged in the conduct constituting the offense, did not know of such condition of the victim.
(b) In any prosecution for an offense under this part, except an offense under section 53a-70b of the general statutes, revision of 1958, revised to January 1, 2019, or section 53a-70 , 53a-70a , 53a-71 , 53a-72a or 53a-72b , it shall be an affirmative defense that the defendant and the alleged victim were, at the time of the alleged offense, living together by mutual consent in a relationship of cohabitation, regardless of the legal status of their relationship.