The title nods to the nursery rhyme of the owl and the pussycat, who sail off together in love, but the poem darkens that sweetness right away. It begins with couples who "kill / one another out of love," and the speaker places himself among them, whether with his wife or with his bookseller. That odd, slightly teasing second option suggests the speaker is not entirely serious, or not entirely settled about who his partner is.
The speaker seems to feel a mix of guilt, recklessness and wry self-awareness. "We must be ruined / minding nothing but lust" sounds like both a confession and a shrug. The killing is probably not literal; it reads as the way desire can wear people down or consume them.
The ending breaks off. "We who" is repeated and left hanging, as if the speaker can't finish the thought, before settling on "we who enchant / playing owls." The mood is playful but uneasy: charm and danger tangled together, with the pretending of lovers hiding something more destructive underneath.