The speaker is about to leave, and the poem is mostly about what they can't bring themselves to say. They ask someone to keep the news from "her" for now, maybe because they aren't ready for her reaction. They promise a letter eventually, but the refrain "not today" keeps pushing the moment away.
The reasons for going feel mixed. The speaker talks about finding their "destined way," which sounds hopeful, yet they also expect to hear "words" about pain, sorrow and a wrong they have done. The poem suggests guilt, though it never says exactly what happened. The line about surviving "at least till May" has a shaky, half-joking tone, as if the speaker is bracing themselves.
The mood is anxious and tender, with a bit of cowardice mixed in. Short lines and repeated phrases make it sound like someone rehearsing a difficult goodbye, wanting to postpone the tears they know will come.