Clever (and BEAUTIFULLY drawn, Abby!), but isn't there a HUGE difference between being happy and simply having your face frozen in an idiot grin?
I don't see how that line makes sense, even in the context of the joke."I'm devastated, to the extent that's an emotion that's separate from happiness!"
Maybe I'm overthinking this (okay, I'm DEFINITELY overthinking this), but wouldn't it be more reasonable, and perhaps even funnier, if the protagonist was simply unable to think of anything unhappy? He loves the bright, gay color of the crime scene tape, is gladdened that neighbors are taking such an interest in his house, is cheered by the fact that his wife will not suffer from her wounds or struggle with old age. His wish-dictated myopia would progressively worsen as his circumstances deteriorate, until at last there are absolutely no happy thoughts available to him—except, of course, for the one in Zach's punchline.
Maybe something like, "The symmetry of those iron bars is so oddly satisfying!"