Might want to read chapter 4 again my friend.
Misaki has a decent reason for having the idea two guys don't work out. He believed he was in a relationship only to be told, "Hey, I'm marrying my girlfriend. That's normal. Not like we can continue like this (or so society says)." That's all he needed to reinforce the idea that two guys would eventually mean being dumped by the other who'll go ahead and marry a girl cause a guy can't have a child. This takes some cultural understanding to grasp, as in Japan and much of Asian culture at that, the idea is that the 'right path' is to establish a family with children to carry on the line. We can argue otherwise, but growing up in developed western countries our limitless freedom makes us forget that there are countries with unspoken rules embedded into one's way of life.
So no, while his personality isn't the best, he was in a relationship and he was abandoned not for his personality, but because he's a guy.
Remember too that it can be hard to see with all the 'online movement' promoting homosexual freedom but two guys or two girls still actually have a fair bit of problems jabbing at them in reality. Just going about their day-to-day lives is equivalent to being bombarded with constant insecurities.
It's not because anyone, in particular, is singling them out but simply the fact that what we see is what we perceive to be true. We can't understand what a dog is no matter how well its described unless we've seen for ourselves what a dog looks like. And what gay guys see projected all around them are male and female couples. This is not to say there aren't male couples out there, but it's just not something seen too often or at all for that matter. And this leads to a lack of understanding regarding what males liking males should be, can be, and 'allowed to be'.
You a very clearly not a gay man huh. As one myself, that was a very realistic part of the story, especially the doubt and self loathing.
Perhaps stop being ignorant and educate yourself about what being gay is actually like instead of basing it all off of yaoi.
*are
Is that how you deal with yourself and other people on an everyday basis?
The way this piece of shit blames everything on him being gay when his disgusting personality is at fault is sickening? Two guys can't be happily in love and can't have any future cause they're gay? Naw bitch, that's you projecting. You keep deluding yourself, saying nobody would like you for being gay just because you don't wanna admit to yourself that the real reason is cause you're a lowly asshole. Imo, he deserves anything bad that happens to him. Maybe if he fixed his personality he wouldn't be so miserable.