Heh, yeah, ok but NTR = netorare = literally "cuckold". Fucking an egirl in front of their simps is not NTR as they do not have a mutual romantic relationship with her.
Actually it does fit the definition because NTR has three forms.No but their relationship with the goblin women is literally servitude in exchange for maybe sex one day. Watching some non goblin dude waltz in there and fuck the shit out of their idol right in front of them after they've been simping on her for years leaves them all with the same feelings as if they'd been NTR'd. It's just a joke, it doesn't need to match up to the dictionary definition of NTR to be funny, it's close enough.
Netorare: Where the cuckold/cuckquean is being cucked without their knowledge until it's too late and it's devastating to them. The goblins that die from cucking are this.
Netorase: Where the cuckold/cuckquean gives permission to their lover to fuck other individuals and enjoys it. The goblin that survives because he likes it is this.
Netori: Where you cuck the cuckold/cuckquean. The Goblin Layer.
Rule of three says its funny.