The slasher kills all the virgins, but the sexually active Battle Couple defeat him.
Alice and Bob realize that they're about to die, and so they decide to go out with a bang. This is Sex By Death, because it is the approach of death that causes the sex.
Alice and Bob have sex, but neither dies as a result.
Alice and Bob wait to have sex so their first time will be special, but one or both dies before the act is consummated.
However, they do die during the series or movie.
Alice has a fatal STD and gives it to Bob through sex. However Bob dies by some cause completely unrelated to the disease.
Alice has a fatal STD and subsequent to them sleeping together, it is revealed that Bob has caught this disease. Later, it is revealed that he already had the disease when he slept with Alice, meaning that the focal sex scene didn't kill him at all.
The slasher walks the Earth, and only goes after couples having sex. ONLY when they're having sex. He backs off during false alarms.
Discussed: "Bob, I can't have sex with you. I like living way too much to do that."
Conversed: "Have you ever noticed characters who live active sex lives always die in horror movies?"
Deconstructed: Alice and Bob decided to take the plunge on very uneven ground in the relationship. They can't really enjoy it because of their standing with each other. They die in very poor conditions, they are also reveled to have been in the act, making many people mad.
Reconstructed: After finding each other and coming into the arena of love near an end in the timer on their life, such as disease or some curse being put on them, Alice and Bob decided to go out in the best physical event possible. During that time they both enjoy it for all it's worth, not being held back by anything or anyone, allowing them to go out in the best way possible.
Played For Laughs: The slasher comes up and sees Alice and Bob in an act of Auto Erotica, rolls his eyes, and blatantly stands there waiting for them to finish.