The great 20th century English poet and literary critic William Empson made a famous analysis of Sonnet 73 in his groundbreaking work Seven Types of Ambiguity. So while this sonnet may be one of Shakespeare's easier poems, that doesn't mean the betweeded ones didn't dissect it within an inch of its life.
Shakespeare married young—at 18. Okay, so that probably wasn't that young for 1582, but when you consider the fact that he married an older woman (Anne Hathaway was 26 at the time), who was already knocked up, things take a turn for the scandalous. (Source.)
Big Willy died at the ripe old age of 52, in 1616. Well, ripe old age for the English Renaissance. In any case, he definitely lived long enough to know what this sonnet was all about. (Source.)