Okay I am a little more calm, let me give you full context.
The man being choked is Wegg, he was cursed by a cult, and has to die every 35 days to avoid a worse fate. So his partner, Mr. Neighbor, (who is also a serial killer) helps him by killing him once a month. This time, after having watched a slasher film, decided to end the cycle during bdsm sex. This is the part when Wegg confirms it's time to kill him, and Mr. Neighbor snaps his neck.
This scene is so powerful to me, it shows the consent, the communication. Intimacy and love, intermingled with destruction and death. I don't know how to explain it, but it's just. Wow. I love it so much.