He didn't think that he had the rights to be happy, since he didn't spend more time with her in life (it was like a self inflicted PENITENCE) and didn't honor her memory and he was leaving in the past. But he never walked all over Futaba (heck it is even clearer in the anime adaptation that just ended this week). Even taking her for granted wasn't done in a bad way. Just because he thought she will never forsake him and will be there no matter what, doesn't mean he did it purposely. Hurting Futaba wasn't his goal. It was a byproduct of his blind and apathy towards his life that ended up hurting her. However, he said to Kominato that he was going to help Narumi and then . He had a plan, but it was a naive and stupid plan that didn't work. I don't like when people twist and misunderstand Kou's character (among others, but he is the one being questioned here). He isn't so "mysterious" and "aloof", he is pretty EASY to figure out :P . Its your typical tsundere and not even a very deep tsun tsun either. He is kind of mild. I don't really take sides, I follow the flow of the manga and the author's intent and purposes. The direction is pretty straightforward and it isn't going to change or take a drastic turn south or whichever which way. It is going on a straight line, but taking its stops and goes. It has an order to things and just like Life, its missed opportunities, misunderstandings and bad timings, it is taking its time, but it will sure GET THERE wether people like it or not. It will satisfy the people who has been following it the right way .
I just wanted to say that ^^ and I have my type. I love Youichi Tanaka sensei <3 . But I don't think he'll be good for Futaba and I don't try to ship him with her either -_-, even if the school apparently did, at one point, during the scandal hahaha. The heroine/MC will have the last say on this manga.