NTR is Netorare but NTS which is Netorase is a sub genre of it atleast from what I know. NTR/Netorare is being cheated on by your partner and NTS/Netorase is you willlingly sharing your partner to other people. Atleast from what I understand.
I've never seen NTS used for netorase before. It has always been called NTR, regardless of whether it is netorare, netorase, or netori.
EDIT: Even urban dictionary doesn't have netorase as a "definition" for NTS. It does for NTR though.
EDIT EDIT: Actually had to go down further (6 "refreshes") to find one. So first edit is incorrect, albeit just barely.
Really? eh might be because Its one of the genres I follow so I got used to using that abbreviation. Most games containing netorase content I've seen people use that abbreviation. Threads from a certain pirate site, steam curator pages, some Itch collections and some games here use that as a tag, some steam and reddit discussions used the abbreviation. I guess I got used to using it since Its a genre I follow I thought it was a known abbreviation.