“think of the proverbial unexpected outbursts of the beloved: ‘I love you’ which surprises even the one who utters it.”
This 'unexpected outburst' is, simultaneously, a realisation and an inauguration of a state of affairs, an event. A birth, like a note out of silence, a silence which (afterwards) we take to have been pregnant with unresolved tensions. It is, among other things, an instance of the performative magic of the signifier.
C.f. the experience of saying something which is ‘not what I meant’/ ‘I didn’t intend that’ – that is, it is not that one has a fully formed content to communicate which one then ‘fails to express’ – it is only after saying something that one realizes it is 'not what one meant'. Only once speech has missed the mark can one see the mark itself.
‘What one intended’ thus flashes into view ‘in arrears’.