Acronym for sexually transmitted expectation: a chronic, debilitating, and rarely fatal disease caused by consensual sexual contact. Oddly, STX is passed by an uninfected carrier to an unsuspecting patient. The hallmark of an STX diagnosis is manifestation in only one of the sexual partners.
Neither Sally nor Ray had a habit of telephoning one another. Then they had sex. Sally, the unsuspecting patient, contracted an unfortunate STX which now makes it medically impossible for her to understand why Ray does not call. Ray is oblivious to Sally's disease because he is an uninfected carrier. But he will not call under any circumstances, not even if Sally makes a miraculous recovery.