Secondly, by ‘sharing’ in this context, I mean sharing a partner you already have an established romantic relationship with. Jessica is a side character, not an LI, who also has a negative tone toward Mia, who is one of the LIs. From that perspective, I don’t personally see it as sharing. I might be using the terminology incorrectly but as I’ve already said, you always have the choice not to take that route.
You can of course redefine what "sharing" means, and you can also redefine NTR, NTS however you want. You can casually create a bunch of sex scenes that have nothing to do with love interests.
So can you tell me, in this game of yours, who exactly is the love interest and who isn't? It's fine if you don't say — the final right of interpretation is in your hands anyway.
First of all, Jessica is not a paid prostitute. She has flirting options, she has blowjob scenes — normally in a harem game, that would make her a love interest.
If you don't know what a harem game is, then go play a few first before talking about wanting to make a harem game.
Second, no one in their right mind would design a BBC character named Tyrone in a harem game, make him the protagonist's best friend, and then have him sexually harass the protagonist's family members.
I suggest you should just go develop an NTR game instead. You clearly have the talent for it.Lastly, if my comment gets deleted again, I'll just post it again.
Also, don't make promises you can't possibly keep. In serious cases, this can lead to legal risks.