A speaker plans another evening with a lover and already sees how it will end up. They'll talk, drink wine, laugh, and maybe have sex, all while the light fades outside and the garden flowers lose their colour. The couple barely notices this, aside from a vague "ineffable sense of absence" that hangs over the night.
The poem begins and ends with the same question, "Why do we do this to ourselves?" and then "to each other?", and that small change matters. The speaker moves from blaming themselves to admitting that both people are caught in the same habit. They go on meeting even though they know the closeness is temporary and that a vast distance sits between them, even when they're in the same room.
The mood is quiet, tired and sad. The evening is described as "fun," but the speaker doesn't seem to believe in it. The loneliness, the poem says, will win.