I first read this poem in the introduction to an anthology called something like The Sonnet, but it was originally collected in a 1921 book of Frank Sidgwick's poems called More Verse; you'll find it there on page 47.
The Aeronaut to his Lady
-- Frank Sidgwick
I don't have the book handy, so I might be wrong; but my memory is that the anthology where I originally read this poem quotes it only in the introduction, and says that it is "clearly intended to be a sonnet" -- far too much hesitation, as it happens, since in More Verse it's published as the second of a little collection called "Two Sonnets": Sidgiwck meant it as a sonnet, tout court, and I think he's not wrong to consider it such.
I'd quote the other of the pair, but frankly it's not nearly as charming as "The Aeronaut to His Lady" -- not nearly as charming as it's trying to be. If you want to read it, click through to the book and have a look for yourself; but I wouldn't particularly recommend it. Sidgwick's Aeronaut, on the other hand, is a keeper.