Second time seeing an ending like this. The first one is otomekuzushi from carn. I want to see more story like this, where the mc wasn't running away like some ntr stories and blow away the culprit. (The raper in this story was killed in the end)
In the end the mc said that all of this was his story 10 years ago. He finally married her and have a children. He doesn't know if the child was his own or the raper, but he will always protect his family from now on.
By the way, is this count as ntr? because the girl never said or give sign that she was more happy with the raper than the mc. This was more like rape than NTR.