I can see what you are talking about however i think when the ladie's partner is complete dick to her netori wouldn't spoil the mood of the game much. i hate cheating if the cucked party don't deserve it.
I mean, that's kind of happening. After all MC is fucking the major's wife and will have sex with Kim's wife Liu, too, for example. Most people probably think of actual netorare when they hear NTR and until now there's no indication for that, even though the devs had perfect opprotunities for a proper buildup with the mafia/main story.
In the end DC seems to be a pertty grounded guy, so the rule will likely stay that "the good guys" like Harold, Erik, Earl, etc. will get a proper excuse/alternative while the bad guys like Dexter, the major, Kim, etc. will have to suffer a little more.
Expected release date of next update ??
Nobody knows and recently it became even more unpredictable. But I wouldn't expect anything before mid january or so.