It was a perfect marriage. She didn’t want to and he couldn’t.

Milligan’s line is a compressed, darkly comic inversion of the “perfect marriage” cliché. By reducing marital harmony to a mutual absence of desire and ability—“She didn’t want to and he couldn’t”—it satirizes the gap between social ideals of marriage and the private realities of incompatibility, resentment, or sexual dysfunction. The joke depends on abrupt ellipsis: the reader supplies what “to” refers to (sex, intimacy, or even the marriage itself), and the punch lands by pairing refusal with incapacity. Typical of Milligan’s mordant wit, it treats a painful subject with deadpan economy, exposing how relationships can persist not through love but through stalemate.