There was no need to act immediately. People could have been informed by a public campaign this specific change was coming in, and been given say two years to make any changes to circumstances they needed. But no, act as if people are not involved at all. That was the "fairly inevitable"

"Could have been given two years"? Instead they've only had a year and a half (1 Jan 2020 to 30 June 2021). It shouldn't need a public information campaign. Anyone wishing to marry has to apply for a marriage license, at that stage they would be reminded of the rules.