Thank you for the clarification. I am not well versed in the terminology as you might tell.
So any form of cheating is NTR. I guess the NTR games I have seen up to this point had cuckoldry so I must have connected it in my head.
Well, not exactly
NTR isn't just about cheating, it's more complex than that
As far as I understand it (and I'm not well versed on all of this either), NTR is specifically when a girl cheats on her partner, without her partner's knowledge or consent
In most cases, the definition also includes the girl not wanting to cheat initially, but over the course of the story realizing she loves doing so
And the core essence of the story is the partner learning about the cheating, and diving into the dark emotions it triggers within him, where the focus is that the main character (who is being cheated on) doesn't like it
At least, that's what I could gather from everything I've read about it from people here, and comparing some of the definitions I found online
It does seem that cuckoldry is one way to create an NTR story, especially after the partner learns about the cheating, I guess it's easier to write stories that way