are all correct, except for the capitalised H of he in the first. The first expresses regret about the non-occurrence of a mind-change and subsequent marriage in the past. The second expresses regret about the probable non-occurrence of a mind-change and marriage in the future.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
fivejedjonexpresses regret about the non-occurrence ... regret about the probable non-occurrenceFantastic! I would have never thought of wording it that way.