I found this NTS game on dlsite and played it and it's really interesting. It's called 妻が過去にしてきたエッチを聞きながらラブラブセックスをする話 [RJ01079592]. It's the most vanilla NTS I've ever seen.

You know that idea of the NTS where the girl never fucks anyone and just pretends she does and makes up these stories of her with other men to get hubbie off? It's kinda like that. He comes out to her about his fetish and she's like I know, I saw your search history, you're into netorase, right? And he corrects her by saying that actually no, he doesn't actually want her to sleep with other men, he just wants to hear her experiences with other men from past relationships. So that's what happens, they slowly go over her history with her 4 prior partners. How they met, the first times she had with them, how the relationships went and then ended. All while doing tons of lovey dovey sex. It actually works surprisingly well. It manages to be much more exciting than I thought.

However, it does end up feeling a little unsatisfying that it never culminates in a share. At least one would've made for a great climax. But I respect what the dev was going for, and they did it really well.

The game has a sequel where they go over some more details of the past relationships and it's interspersed with flashbacks from her POV. Unfortunately these kinda ruined the sequel for me. Instead of being hot, those flashbacks just feel kinda depressing. They were all kind of shitty or unhealthy for her in some way. There's good reasons why they're not the man she married. And also, since they're flashbacks before meeting hubbie, they don't really scratch the NTS itch. Overall disappointed, but still respect what the dev did. I hope they do more NTS stories in the future, and add a little more spice next time.