SKIP THE FIRST STORY (aka chapter 1). Seriously the main love interest is terrible and puts his fetish before the actual person he's dating. He also can't read the mood to save his life (or his relationship). The second relationship is really sweet though! (if a little bit stalkerish at times) The main guy finds a dude that is constantly doing the right thing at the wrong time in the wrong place, so he's considered a troublemaker even though he's genuinely just trying to help. Main guy decides that he wants to marry the heroic tsundere in highschool, but looses track of him when the other guy gets expelled over a misunderstanding. Years later, he finds the guy again, and takes him home and does all but tackle him yelling "Mine!". It's great.
Saiaku no Jinsei