1. Play without mods
2. Choose with all the girls "sex relationship". With Kari you will tell her that you are going to try the relationship.
3. With Kari never tell her that you love her, "I want to keep my options open".
4. Turn them into your slaves (submissive).
5. Whenever you can, go to the swinging club.
I have been able to verify that the last update ends after Kari proposes to you to be your slave/submissive. Hope it helps.
There are 2 swinging scenes, one with lois, and another one with Kiki.
First up, let me say that everything below is optional/avoidable content;
There is also the option to have Kari "Roleplay" as whoring herself out. This has you walking in on her counting the money from a guy you see leaving the room she is in. Kari then tells you about how she has been offering these services for extra cash. You can choose to end the "roleplay" at which point the game continues on. You can also choose something like "Lie about going home" and "Continue the 'roleplay' ".
If you choose to continue the "roleplay" or 'not go home' option, you get a scene where Kari fucks another guy.
I am not sure why this hasn't added the NTR tag to the game yet. As I said all of this is optional and avoidable, however, I don't think that should exempt it from NTR tag... You can't really just say 'hey its just roleplay' or whatever and dance around proper tagging...
I mean even the Developer refers to it as NTR in-game when presenting the warnings and such...
I don't really care about the addition of optional content, I DO CARE about accurate tags, transparency and giving players correct information.