A writer is typing fast, then stops to reread and finds holes in the text. A word or two has dropped out, because his thoughts moved faster than his fingers could follow. It sounds like a small, everyday annoyance, and the poem begins in that practical, almost technical tone.
The second stanza lets the frustration grow. He can type blindfolded, and the words were clearly formed in his mind and almost spoken, yet they still slipped away. The short broken lines, "Slipped – / Missing – / Blank –", mimic the gaps themselves. Then the poem turns. The speaker is anguished, and the final question lands with real force: has he failed to say "I love you"? The missing words are no longer just typos. They stand for the fear that the most important feelings are the ones that go unspoken or unwritten, even when they are fully felt. The mood moves from mild irritation to quiet, tender worry.