Yeah NTR Knight gives more of a voyeur/corruption feel than a NTR feel. The story fails to build up a solid romantic connection between the MC and the female protagonist so it doesn't really hit hard emotionally when she has sex with another guy.
I honestly think that NTR is very popular because it is a combination of a bunch of different fetishes.
An NTR game can have the following (not a complete list):
Fetishes for the Girl: Virginity Loss, Rough Sex/Hard Sex/Rape, Impregnation, Corruption, Submission, Cheating, Sharing, Swapping, Gangbang, Mother/Sister, Childhood Friend, Wife, Girlfriend, Crush, Fiance
Fetishes for the MC: Netorare, Netorase, Voyeurism, Humiliation, Cuckoldry, Cheating, Sharing, Swapping, Masochism, Wimp, Small Dick, Husband
Fetishes for the Bull: Netori, Domination, Breeding, Sadism, Ugly Bastard, Chad/Tyrone, Bully, Boss, Brat, Big Dick
NTR games are usually a mix of some but not all of these fetishes. As long as you know which of these fetishes you like, you'll be able to find the right games.