The speaker is in a low moment, mentally listing everything that has gone wrong. The phrase "catalogue of misfortune" makes grief sound almost clerical, as if the troubles are being tallied one by one. Then the eyes drift away from that list and settle on a single swan in a park.
The last line changes everything: this is the park where the speaker met their wife. The poem never says what has happened to her or to the marriage, and that silence matters. The swan is alone, and the speaker may feel alone too, though the poem only hints at this. The place carries happy memory, but now it sits beside loss, which makes the comfort uneasy.
The title suggests the swan offers some quiet solace, like a therapy animal. The mood is hushed, tender and sad. Short lines and a trailing ending leave the feeling unresolved, as if the speaker is still looking.