If you have to explain why it’s late for three paragraphs, you already know why it’s late.

Length is a clue. A genuine obstacle fits in one sentence and everybody understands it straight away. When the account starts stretching, it is usually doing a different job, which is managing how you feel about the real answer rather than informing anybody. You are not lying, you are cushioning, and most of the cushioning is aimed at yourself.

Write the one-line version first and see whether it holds. Send that, with a date for when the thing will actually be finished. Then put the rest of that energy into the work instead.