Hello Nerva. Not sure if you got an answer to your question from several weeks ago but I do see the question come up often so for other's looking for an answer, here are a couple of possibilities:
NRaas Retuner does not have a direct mod for Jealousy but there are settings for Accuse of Cheating, etc. From City Hall or a Computer>NRaas>Retuner>General>Social Interacions.
There is another mod over there that will disable jealousy completely or allow you to adjust the levels however due to the Teen Rating factor I do not believe I should be linking to that particular mod in this forum. There are more discussion threads in relation to multiple relationships and links available over at NRaas. I'd ask those questions over there in Chatterbox.