First I'd like to say.
Best Childhood Friend EVAR!
But because she wasn't a potential interest they threw Mika in, though it was done pretty well.
Yandere done to a tolerable degree, or more accurately I guess the manga(though not a credible source for reality) is kind of proving that Yandere's CAN find love and be loved if you deal with their personality properly.
MariAli767 brings up a good point, however usually it's a case of what I call "Wrap It Up". Meaning they didn't really have all that much chapter space allotted to build upon the story, with the end we have to assume they found some sort of middle ground since they managed to stay together for at least 14 years.
Compared to Yankee-kun to Megane-chan where the ending was...."And the hijinks will continue..." I'll take the ending where some issues weren't completely addressed as long as I know they ended up "Married With Children(Child)"