Well said, this is netori, not netorare.
This. It's a netorare-style story, though, rather than a netori-style story. And to explain that, netorare-style usually has the douchebag being the one stealing away rather than being the one being stolen from (netori-style). To anyone who might ask "what's the difference?", what the type actually is, is dependent solely on who the main character is, which is why it's properly classified netori, not netorare (we follow the douchebag doing the stealing, not the one being stolen from).
While NTR usually stands for netorare, it can also stand for netori or netorase. In this case, it is netori so it can be described as NTR
Not accurately. NTR is NeToRare, or in Kanji, [寝取られ], means "cheating
with", referring
to the act itself rather than to an individual (the way it was explained to me was that it's the difference between saying "It's a robbery!" vs. "It's a robber!"), and it is based off of Netorareru [寝取られる], which is the passive form of Netoru, and can be conjugated further, eg.
kanojo ga yuujin ni netorareru [彼女が友人に寝取られる], which translates to, "The girlfriend is
netoru'd by a friend". We can see this proven by looking at the root word Netoru [寝取る], which also forms the root for Netori [寝取り] and Netorase [寝取らせ], and means solely, "to sleep with a girl (or guy) that's already sleeping with someone else", aka cheating. Netori is the active form of cheating, meaning literally, "stealing someone else's partner". Netorase is the causative form of Netoru, meaning letting or forcing someone to netoru someone; this could be something like the storyline of the H-game Euphoria, where rape is forced by threat of execution, to something where a couple goes to a bar, finds someone that they want the wife to fuck, and they take him home so the man can watch (and maybe fuck her afterwards).
Now, why did Netorare become so popular over Netori, such that the former became very well known before the latter really surfaced in the anime/manga-loving zeitgeist beyond Japan? No fucking clue. Maybe just there's more masochists than sadists (which would sorta be supported by the "herbivorous men" stereotype of Japanese men, likely caused by social and work pressures, stress, and the reality that marriage simply isn't necessary in this day and age anymore).