Yunior’s got this problem. Here he is, a college professor, with a taste for kalbi and Sichuan, teaching Intro to Fiction. Not bad for a middle-aged Dominican from a Jersey barrio. But his fiancée left him after discovering he’d been doing for a long time what she told him she’d machete him for, cheating.

So he suffers. Emotionally, sure. But his body is piling aging’s complaints atop those of his ex. Then a law student half his age, a post-breakup hookup, leaves him, too, for someone younger—then returns pregnant. A machete might have been kind.

“It feels like you’re slowly being pincered apart, atom by atom,” Yunior tells us in “The Cheater’s Guide to Love,” the final, remarkable story in Junot Díaz’s This Is How You Lose Her. The stories in this collection check in on iterations of Yunior over the years, from his 1970s arrival in the U.S. with his mother and older brother Rafa, joining the father he’d never known, to the weed-smoking teen chasing blanquitas while Rafa dies of cancer, to the lit prof who left the street that never quite leaves him.

Yunior is a recurring character in Díaz’s fiction, both in a previous story collection, Drown, and his first, Pulitzer Prize-winning novel, The Brief Wondrous Life of Oscar Wao. His arc is much like the author’s, although recently Díaz, an MIT professor, told an interviewer from USA Today he is not Yunior: “I wish! It would be far easier. I wouldn’t have to do any work. You can give characters your vida, but they are certainly not you.”

Maybe. Yunior seems not so much alter ego as an equally brilliant doppelgänger somehow bereft of the author’s insight—despite being one, too. He’s blind to the obvious, that he has not patriarchal culture but his own moral failings to blame. In the first story, “The Sun, the Moon, the Stars,” he attempts a rapprochement with a trip to his homeland. But she stays frosty and he turns feisty: “I was thinking, For this I deserve something nice. Something physical.” Uh … yeah.

Díaz writes in a bracing argot that laces references to Joyce and Melville through a Spanglish that is slanglish, full of fly’s and like’s. Through Yunior’s foibles, Díaz examines complex cultural anxieties without seeming to. Racism, sexism and imperialism haunt these stories, but as givens noted in passing. So Díaz avoids banality as Yunior dodges wisdom.