The poem we know as "Methought I Saw my Late Espoused Saint" is John Milton's twenty-third sonnet and was not given a title in its first publication. It was literally just called Sonnet 23. Super creative, we know.
Since then, we've come to know it as "Methought I Saw my Late Espoused Saint" or, according to some editors, "On His Deceased Wife." Whatever the case, the point here is that this is a poem about a sad guy's dead wife. So, in short, prepare yourselves for a downer.