Well, NTR (Netorare) IS a japanese term, but is also commonly used in western porn games and comics.
Broadly speaking, it is different from mere cheating.
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is an explanation of NTR with references to the root of the word itself.
But NTR is one of those topics that gets people extremely excited, both negatively and positively. Hardly any tag is more divided between those who like it and those who hate it.
You can see endless discussions about anything NTR related here on F95zone. It has even become somewhat of a meme.
If you don't want all that hassle, simple don't use the japanese terms and only use English equivalents.