I think it was obvious how much of an asshole kou was from the start, how are you supposed to trust a one-night stand? And that one-night even sexually harrassed him in his own office, not a indication of a good guy in anyway. It's kind of yaoi's fault that we have kind of accepted these kind of things as cliche, because when you think about it, the way kou treated shinobu initially was very problematic even before it got revealed that he betrayed him, just because you was kind once in a while doesn't make those initial assholeness go away.
I also like the way shinobu handled it and didn't forgive him easily. Definitely liked his backbone and also liked how he took the relationship back at his term, in the future I imagine if you once again does something shitty shinobu will just dump his ass and move, he certainly has the maturity to do that.
I was a little shocked that the seme was just using the uke for fun, I totally didn't see that one coming. To me the author gave no hints at all, it seemed like a classical love at first sight with a top notch seme that sweeps the uke of his feet and shows him how precious he is (kind of a cliche of the genre).
BUT it wasn't like that at all. So the asshole seme routine had me totally blindsided. My heart broke for Shinobu when he saw Kou with the other guy in front of the apartment and when he overheard said guy talking with his friend.
I was really glad Shinobu had a fucking backbone and didn't just confront the seme in tears begging him for answers and to reconsider. I was also fucking thrilled that when Kou tried to fist apologies he was met with nothing but contempt from from Shinobu, since usually the uke just jumps into the seme's arms being all happy he returns his feelings.
So yeah, great job Shinobu making him work for it. I think the only thing that would have made this more satisfying would have been if another love rival showed up for Kou and Shinobu would have made him suffer more by giving the other guy attention. ╮(￣▽￣)╭