I saw this a few years ago (2-5) on TV, could be quite old but it isn’t fresh enough in my memory to say whether or not it looked like it could be old/new. Definitely at least 5 years old I would say.
So the plot involved a group of survivors that stumbled upon two people (a man and a woman) that offered to let the group stay with them. Over the next few days, everyone in the group started to get more trustful of the two people that took them in, and I think at some point they may have had a mild orgy. Towards the end I think a lot of the people from the orginal group have died and only ~2 remain, along with the man and woman that took them in. The two remaining survivors had been weary of their hosts, and it turns out they were right in doing so, as they had killed the other survivors (maybe by drugging them, or they might have had some kind of power, not sure).
That is as much as I can remember, and some points may be a little off as my memory of this film is weak, but I hope someone can tell me which movie this is as me and a friend have been wondering about it for weeks.
I think you are referring to Teenage Caveman. It’s post apocalyptic and the teens are saved by a man and woman. They have an orgy, lots of sex and drugs, and the man gets jealous/goes crazy and mutates. In the end, only a male survivor remains, after killing the man/monster with a grenade. He goes back to his tribe and takes the rest of the kids. This it?