NTR
Japanese acronym for Netorare, used to define a genre of Eroge (Hentai Game), meaning "Cuckold". In short, the main protagonist's loved one(s) are taken or seduced away from him and the heroine might be willing or unwilling. This is to cause an emotion of deep jealousy on the reader.
I was referring to its affect on me as a reader :3
My main point is just that it felt NTR to me personally! And, it kinda is.
I guess I'm just not a fan of the 'get married and still fuck other people' plot? Willing or otherwise.
But yeah, Miyabi is a lighthearted writer, I just question some of his stories morals... this one and Stay Tune (the ending to this one also pissed me off).
This is all purely my personal opinion though. Others' are free to interpret the ending as they wish :)