Ore ni Koi Shite Dousunda

From Vices and Devices:

When his interior designer mom takes off to New York for a year, Toranosuke, dorky name notwithstanding, gets sent to stay with his uncle. And it's just his luck that Ryouji is obnoxious, violent, and has the same sharp tongue as Tora's mom. Only it turns out that he's not really that bad, and maybe Tora is falling in love (with his uncle, of all people), and Ryouji has a heart of gold underneath the bellowing and violence. Except that Ryouji's pretty much the worst guy in the world to fall for: he enjoys sex more than eating, has a commitment problem, and has long since convinced himself that he's really, really straight.