I'm just afraid the ntr on/off is a scam, such as The Engagement. ntr Off just don't let the player see that scene.Firstly - it's not netorare but instead - netorase, where you willingly share and participate.
Secondly - if you don't want netorase, just don't go down those routes, they're clearly showcased as such. If you won't pick em you'll go down the harem route. 2 simple paths to pick with each girl.