What is enemies with benefits?

I recently had this, I just had them become basic friends (like friendship bar one quarter full), then had him flirt and compliment her appearance over and over (they seem to be the only flirty interactions my Sims will absolutely accept when they are not good friends) until the romance bar was high enough to try more romance interactions and eventually WooHoo. I made them WooHoo their way to the highest romance bar, but their friendship level also kind of went up too... I had to have my male Sim be kind of mean to her, then have my female Sim be the one to initiate romantic interactions (she would have been too angry to accept them from him). With a bit of fiddling I eventually got their romance bar to pretty much the max and their friendship bar to like complete hatred. I had them continue an enemies with benefits relationship until eventually my female Sim got a boyfriend and my male Sim saw them kissing, and he got some kind of jealousy moodlet related to the enemies with benefits thing but I can't remember what it said now. I think it was something like 'maybe more than just enemies with benefits?' or something along those lines but I could be dead wrong.