It'd have been better as an NTR hentai and I could fap and easily get it over with. The story and characters which started with such a decent and wholesome premise took little time to go downhill further and further. The only thing that improved was the art and the coloured panels. Around chapter 136, it made me so restless that I stopped waiting for the translations and read the raws directly. And here's my short comment on everything that happened:

It is cheating and NTR, fully, no excuses, no over-estimation. With a premise where characters are in a relationship and things go awry, it's okay to hope for developments to happen with side characters but when they are married, it is totally unforgivable. I don't know if that sensei is just too trusting of Asami or has a really bad understanding of reality, but he is too forgiving for situations that'd lead to dire consequences in real life. I know this is fiction and doesn't really need to emulate real life scenaries, but when things take such a sharp turn that it even passes the supernatural, it is to be pointed out for simply being unaccecptable. Asami is also no less than retarded. It is during the middle section of the manga that you will find yourself unable to root for or relate to anyone. However, I still continued reading hoped that they'd change. But no, retardation can not be cured, and especially foolish couple who have nothing to do with each-other but overly kind to everyone else is just too much to cope with and nothing is to be solved. They are just to be forgotten while they are still in the darkness.

TL;DR: Wife is faithful to husband but retarded as hell so much that she can't reject other's advances to the point of almost having sex with them. The husband is an indecisive man suffering with sudden strokes of depression due to his wife's actions, but still trusts his wife too much. Both are, however, good people as the author wants to portray.

Just divorce already!

P.S.: There is, technically, still a 'happy' ending.