Nice one, though I must be far gone considering "the line" didn't make me blink haha!
Also, you might consider that a succubus is probably more in tune and aware of sexual matters, even the faint trace of semen from yesterday might be enough. Especially if she can, you know, die from it.
Honestly, I liked it. I liked the premise, I liked the collars. Other people's promiscuity or sexuality aren't of my business so I don't want to be bothered by it. But still, it's a shame how that one line felt really um, obstacle-y, to the mood it had going on. But still, they have a nice thing going on, so I'd still like to see more