There are two songs called You’re My Best Friend. One was sung by Freddie Mercury, the other by country croaker Don King. Who knew they’d become the anthems of 21^st century love and marriage?

The hot and crazy pre-destined soulmate has been dropped from marriage-speak for the rock-steady, logical-thinking best friend.

Common sense says that a long-lasting relationship should successfully move from the car-crashing madness of falling in love to a more rounded mateship involving conversation.

But was it always talked about so positively? Because it seems that telling the world your spouse is your best friend has taken the place of old-fashion courtship arrogance – where nobody else could have ever felt so throbbingly alive.

Instead, the smug and secure thing to do is sit in our matching armchairs and have an affirming chat. Social science says so.

In 1993, a US study found that 44 per cent of college students regarded their romantic interest as their best friend.

That figure has almost doubled. In February 2017, Dr Gary Lewandowski, professor and chair of psychology at Monmouth University, New Jersey, published results of a poll on best-friendship and marriage.

He found that 83 per cent of American adults currently in a relationship regard their current partner as their best friend, including 88 per cent of those who are married and 72 per cent in a non-marital relationship.

View this post on Instagram

A post shared by Kate Upton (@kateupton)

So what happened in the last quarter of a century? Has economic rationalism, too much sharing of news online, and chronic political uncertainty caused people to search for security and reliability?

This seems to be Professor Lewandowski’s message. Writing on the university website, he says: “Though romantic, believing in soulmates isn’t necessarily ideal for your relationship. The research indicates that those who believe in soulmates and destiny are actually more likely to break up. On the other hand, those who believe that relationships grow over time have more stable relationships and are better at dealing with conflict.”

He notes that when researchers asked couples who have been married for more than 15 years why their relationship lasted, “the top reason was that their partner is their best friend”.

But there are certain issues to be aware of.

Andrew King is the Practice Specialist, Groupwork and Community Education Manager at Relationships Australia, NSW. He agrees that “many people have a partner that they regard as a best friend”.

While this provides a “wonderful opportunity” for strengthening intimacy in a relationship, via the sharing of common interests and aspirations, he cautions: “It is problematic when only one person holds this privileged position in your life as you may expect too much of them, your relationship may change or end as you grow apart.

“Continuing to grow together is the big challenge for relationships in the 21st century.”

Mr King says that even if your partner is your best friend, you need to have your relationship refreshed by each person living their own life, their own network of friends and interests.

“When this occurs, your friendship will be replenished, and you will continue to grow together. Having a partner as a best friend where there is little space apart often becomes toxic… and dysfunctional.”

The issue was debated at length recently in The New York Times in which best-friendship was characterised as a sign of security, but could also be a red flag for avoiding conflict.

Amir Levine, a psychiatrist and neuroscientist at Columbia University and the co-author of Attached, told the Times that the term “friendship” is an “underwhelming representation” of what goes on between two people in an intimate relationship.

Dr Levine says that it’s through sexual intimacy that couples attain a sense of security relatively quickly. It’s this feeling of security, says Dr Levine, that leads us to describe our spouses as “friends” – but the language is wrong, because couples still need “maintenance sex” to renew attachment.

He says calling each other friends is “an underwhelming representation of what’s going on,” he said.

Melbourne-based psychologist and social commentator Lyn Bender says that couples hold each other to a higher standard than friends – there’s a different dynamic that requires nuance.

“The risk is to take that other person for granted … where you share every unhappy thought or momentary dissatisfaction. There’s not as much at stake when sharing that maybe you’re feeling a bit bored or that your wife’s friends get on your nerves.’’