Just how should a gay couple celebrate its 10th anniversary? With a wedding that’s illegal in 49 states? Jolie-style, with his-and-his S&M-lite tattoos? Or very, very quietly, to avoid the jinx that destroyed Ellen and Anne? As Dan Savage wrestles with these personal quandaries (should he buy into a traditionally heterosexual institution or create his own?), he lays out an intelligent, eloquent defense of gay marriage in The Commitment, drawing on an arsenal that includes 13th-century wedding law, Plato, and even the Bible. But this is no sexless marriage: Savage’s fourth book is true to his ribald, hilarious advice column, veering gleefully into cake fetishism, his granny’s premarital hanky-panky, and the hotness of his boyfriend, Terry, in a Speedo — which, let’s face it, probably trumped all those pesky philosophical questions.