[The Devil’s Temptation] please help explain the imprint problem

So I just read [The Devil’s Temptation] and it was great. However I don’t understand how the three of them having sex helps Hyun MC’s pheromone withdrawal. And why were Ivan ML1 and Alek ML2 so sick afterwards? There was transference of some kind. Alek somehow “released” Hyun but the mark was still there. Please help! 😭.

BACKGROUND INFO serious SPOILER
Hyun MC (Owl Tribe) gets an imprint mark from one of the MLs (both Snake Tribe). We think it’s Ivan ML1 but it’s actually Alek ML2. The imprinter and imprinted must spend time together or else the imprinted will go into withdrawal and shock. Ivan and Hyun are in love but the more time Ivan spends with Hyun, the sicker Hyun gets because he isn’t getting the pheromones he really needs which is Alek’s. Since Hyun becomes immune to pheromone suppressants, he has to have sex with Alek but Hyun wants/needs Ivan there. Hence, threesome.

And Ivan and Alek are cousins.

It’s a fun and actually a very green read 😁