The inclusion or exclusion of Cheating or BSS as NTR is a Flame War topic...
I'll just leave a reference. This page
Difference Between Netori And Netorare is pretty good for netori and netorare but doesn't discuss netorase.
Short excerpt:
Netori and Netorare, while closely related, present distinctly different narratives in romantic storytelling. Netori, essentially, involves a protagonist actively “stealing” someone’s partner, whereas Netorare—often termed NTR—engages the reader through the agony of a protagonist whose partner is unfaithful. Though they share thematic elements of romance and betrayal, the pivotal difference lies in the narrative perspective and the emotional journey of the characters involved.