•His jealousy stems from being very possessive. Nnoitra would think his s/o really belongs to him and if anyone tried to interrupt that idea then he’d be pissed and wouldn’t be afraid to take it out on the offending person and his s/o

•He’ll also go on a long rant/intimidating lecture about how they’re his and ‘he’s the only one allowed to do _____ or _____’ like cliche crazy talk from Nnoitra, especially knowing they were possibly making him jealous on purpose. He thinks it’s humiliating too, so that would not bode well with him 

•Not that he isn’t normally like this, but he’d crack down on his domineering and possessive tendencies and won’t let anyone talk or even look at his s/o

•It’s easy to work him up and he’s also very forward/kinda cliche with the tactics he uses to remind them that they shouldn’t make him jealous. So very rough and dominating sex would be a go-to for him

•Also not opposed to going to any lengths to make sure they don’t do it again. He’ll legit tie them up and keep them in his room or something, just to ensure that they don’t get out, and to let them know how serious he is