I prefer to use this more literal Japanese definition since the West can't decide on the meaning of Netoru.
In Japan, the abbreviation NTR is mostly used for Netoru, which is more neutral (third person). It's from this that the terms netorare, netorase, and netori originate.
netoru (寝取る) 寝 to lie down, to sleep (in this case, to have sex), 取 to take, to steal, to assume, to seize, る husband, wife, someone's partner.
To sexually steal someone's (wife or husband).
Genre: The feeling of betrayal, envy, loneliness, abandonment, robbery, and loss, and inferiority, incapacity and sexual incompetence.
Uwaki (浮気) in Japanese, which does not carry with it the idea of theft or loss, of taking, tori (取) from someone else, not the "negative" part of netoru, the partner's betrayal is never discovered, either the partner agrees or both betray and don't care.
Netorare which would mean the act of Netorareru (寝取られる) is the passive form of netoru
Your (wife or husband) is being sexually robbed from you.
netorare does not mean "cuckold," it refers to the act.
Netorareta (Cuckold) a man whose wife has been stolen from him.
Netorase which would mean the act of Netoraseru (寝取らせる)here acting as a cause of your loss.
You and the reason for losing (wife or husband) to someone else.
Netori which would mean the act of Netoreru (寝取れる) If the agent that causes someone's loss.
You sexually steal (wife or husband) from someone.
Sharing is different from any NTRR NTS, as you can see it doesn't have the sense of loss and inferiority without the cuckold, but it's very rare to play with this content.
In Sharing, if the MC is present, it's a threesome MC/girl; she can even comment later, but without comparison, without saying that the other's penis is better, how he ejaculates more, how he lasts longer. That's Netorare (NTS).