The title, French for people who live well and enjoy life, sets up an ironic picture. The poem's "bons vivants" give their attention to card games, and the poem seems to watch them with a mix of affection and unease. They are "light as summertime owls," an odd, slightly dreamy comparison. Owls are night creatures, so the image suggests people who are weightless and a little out of step with ordinary daylight, drifting through their pleasures. Yet the speaker also calls them "a broken sort of people," which hints that the carefree surface covers something damaged.
The middle lines say they live for "quality things / that time will sacrifice." Whatever they treasure, time will eventually give up or destroy. The last two lines turn on a single word: "impossible." The speaker seems to be admitting how hard it is to accept that such evenings must end. The mood is gentle, wistful, and tinged with sadness, like looking back on a good night you know can't be repeated.