Pointing out the high failure rate for marriages might seem particularly mischievous and mean-spirited today, even to those who will be hiding away from televisions and clutching royal wedding sick-bags.
But when researcher Laura McInerney argues that half of marriages are likely to end in divorce (page 21), she does so not to wind up royalists or cheer up republicans. Her focus is why newly-weds and free-school founders are alike: both tend to suffer from a delusion that it will work out for them because they are superior and unique.
This illusion of "false uniqueness" can stop them examining why others with the same ambitions have failed. Too often, they forget the "boring" things, whether they are shared bank accounts or technicalities over staff recruitment and admissions.
While her argument applies to newly-weds in general, the analogy probably does not fit William and Kate. In terms of global attention, they are indeed unique. More pertinently, they cannot be blind to the mistakes of others, as the press has thrust past royal marital disasters in their faces every day since their engagement.
They are also unlikely to be affected by a further trap identified by Ms McInerney: a tendency to be far too optimistic about the prospects of financial support.
Thirty years ago, the NUT's then president felt it necessary to criticise the arrangements for Charles and Diana's marriage ceremony, complaining about the number of bears that may have been killed to make the bearskins for the ceremonial guard. The NUT and NASUWT wasted no time debating wedding headwear at their Easter conferences this week. But both backed motions lambasting free schools, warning that they would "increasingly undermine comprehensive, state education" and that their real motive was "privatisation and deregulation".
The unions may be tickled by the comparison between free-school founders and smug newly-weds. Arguably, a belief that "it will work for us because we're different and special" pervades other Government education policies, too, as they often seem to ignore why similar approaches have failed before.
Unions may also seize on Ms McInerney's findings about charter schools in the US, nearly a third of which have failed. But her research is not proof that free schools are doomed. Instead it shows their founders can succeed if they listen to local teachers and find a way to complement the existing ecosystem of schools rather than appearing arrogant and a threat. In such a case, how would unions respond? Like republicans on royal wedding day, they will want to stick to their principles - but it would be curmudgeonly not to wish the individuals well.