Now that I think about it, a lot of NTR doujins/stories share a lot of similar/identical character archetypes and narrative tropes between them. You could probably do a literary/character analysis on them.
I can see how it ends. Despite the NTR rangers attempt to cuckold the wife, the wife's love and devotion to her husband is so strong, the rangers are awe by such a pure Vanilla woman, that the rangers have an epiphany and renounce their NTR ways, much to the husband's sadness, who accepts defeat and perform his husbandly duties to his wife in bed.
"This woman is too virtuous! Our techniques aren't affecting her at all!"
"Hmph! You've done well to hold on this far Netorarangers!"
"Look! It's NTR Green (Orc)!!"
"....I keep telling you I'm NTR Silver"
A Key and Peele reference. Nice. Will this lead to NTR Sliver quiting because the team keeps calling him NTR Green instead of his actual name (plus double standards racism)?
Red is a Tenga Rocket(body) Blue is a buttplug Jet (head) Black is a double sided dildo Train (legs) Yellow is Anal Beads Tank (Right arm) Pink is an Octopus (Left Arm) And if we had Green (Orc) , he will be an even bigger mecha Orc by WH40K standard.
I was going to say, in my time trying to avoid NTR as much as possible, I don't think I recall any NTR doujin containing a Sadistic Shouta. I've seen plenty of Gym Teachers, Janitors, and School Doctors, though. I suppose they tend to fall under NTR Red.
I think it's more common to occur with settings like "friend" of the young son or a kid of the boss forced to be taken care of by a couple. In those scenarios NTR Blue usually goes after the wife/mother, but may also go after mother-like older siblings. Though NTR blue can kind of just appear in any scenario, such as neighborhood kid taking a teen's girlfriend or wealthy kid taking an idol who was close to her producer.