Indeed.
Not exactly, in fact "western" cuckold is probably what's most related to netorase, as it's basically what you explained at first : netorase is about the girl cheating with the permission of the mc, either because the mc asked her, or she started at first because she knew of his fetish and he allowed it to continue.
vndb tag system is quite robust and explains it better (in fact wish all the ntr stuff was used from vndb) :
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If she falls in love or is fully corrupted by the bull, then the story isn't netorase anymore, it's netorase with a netorare ending.
No, netori is usually from the perspective of the bull, the player is the one stealing the girl from someone else.
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All of this is pretty logical if you take a look at how Japanese "verbs" are conjugated.
Correct, I honestly don't see the point of all this argument while clearly, people into netorare aren't always into netori, and vice versa.
These are very different fetishes under the same "cheating" veneer.
It's like saying sadism is the same as masochism since it can all be under the "SM" umbrella.