When exactly do we have to use the distributive plural?

Question

In a book about wedding stories, I came upon this sentence:

In the seventies, brides and grooms often stayed apart on their wedding day before the ceremony.

I have been taught that we should use distributive plural in cases like "they shook their heads," which doesn't mean they have several heads each but that, since they are more than one person, there are several heads, hence the plural. AsI was reading this book, I wondered, why not write "they often stayed apart on their wedding days" because there are more than one couple.

You can find the book online here: https://books.google.fr/books?id=S25YDQAAQBAJ&pg=PT69&dq=%22apart+on+their+wedding+day%22&hl=fr&sa=X&ved=0ahUKEwjytpu3nPPXAhXQy6QKHTr0DHgQ6AEIJzAA#v=onepage&q=%22apart%20on%20their%20wedding%20day%22&f=false

Thanks.

Answer 1

This is one of those strange exceptions to the rule in English - it's not correct, but it's well understood by native speakers.

Normally, you would expect the plural to be used - multiple weddings for multiple couples - but it doesn't scan as well when read/spoken. This occasionally results in conflicting plural/singular for a handful of phrases where it 'feels' nicer to say it in a particular way.

However, in the example, while it refers to multiple brides and grooms, it refers to their singular wedding day. Readers would interpret this sentence to understand multiple couples and their respective single day.

Strictly, the singular day could be shared by all the people or could be a different day for each person. However in this sentence one considers each person as an individual because it's very unusual to have a shared group wedding ceremony.

It may also be inferring some brides and some grooms, in various combinations. The unfortunate thing about this particular example is that it requires some awareness of recent history in context of marriage practice.

In a pure grammatical sense, the start of the sentence is wrong. For clarity, I would write,

In the seventies, the bride and groom often stayed apart on their wedding day before the ceremony.

The use of "brides and grooms" in the example implies that most/all unmarried couples behaved in this manner, and readers would understand this given context. While it's not grammatically correct, it's one of those evolving aspects of language we can't really stop people from using!

Answer 2

To add on to Christopher Woods' answer:

I agree that this sentence is awkwardly written. It sounds like the writer mixed two thoughts:

... brides and grooms stayed apart on their wedding days.

... brides and grooms stayed apart on the wedding day.

However, as Christopher mentions, it's typical to use the singular for a generic instance of a common, well-known event:

In their speeches on Inauguration Day, many U.S. Presidents have highlighted the need to heal the wounds from a recent, bitterly-fought election campaign by urging the country to "come together".

These are often proper noun names of days, like Christmas or New Year's Day, something that happens regularly or predictably:

Young children often try to wait up for Santa Claus on Christmas Eve.

In this particular case, the writer may also have thought it sounded odd to pluralize "wedding day" because, ideally, individual brides and grooms should have only one wedding day. This is why I would have written instead, "the wedding day".