Wowie the comments are not what I expected!
But agreeing with what others were saying, I don’t think that Ikumi and Tetsuo ever had the healthiest of relationships. There was a lot of toxic codependency, which obviously blew up and boiled over when Tetsuo decided to move to Italy. Not excusing the way Ikumi is acting, but I think his attitude is somewhat typical for someone with lots of innate talent and not that many people around them that aren’t superficial. At least, that’s what i’ve noticed from my own experience with people like that.
Thanks for translating!