When are two people considered a couple? When they’re married or living together? Or when they’re dating and serious about each other? Can the partners to an “affair” also constitute a couple?

For many of us, the question of what makes a couple is of little concern. It’s only when the relationship ends, and Family Law determines who gets what that the definition of a couple becomes intrinsically important.

In the eyes of Australian Family Law, defining a couple decides the financial settlement and division of assets in separation and divorce, which is typically between two people.

But in the case of a failed extramarital affair or even a fling, is the third party entitled to anything in the breakup?

The Family Law Act makes it clear that just because a person is legally married, or in a de facto relationship with someone else, this doesn’t disqualify them from being in a couple with another person.

Once upon a time, a couple used to be defined as two people who were legally married. The amendments to the Family Law Act in 2009 meant that two people living in a de facto relationship, whether the same or different sex, qualified the parties as a couple. From that time, de facto couples were treated under the law practically like legally married couples.

To qualify as a de facto relationship under the Family Law Act, the requirement was (and still is) that the parties have lived together for two years, had a child together or made substantial contributions for the benefit of the other partner, for which it would be unjust for the law not to recognise.

Family Law also defines living together. It views a couple as two people who have lived together on a “genuine domestic basis”. This considers such things as the duration and nature of the relationship; whether a sexual relationship existed; financial independence and ownership of property; mutual commitment to a shared life; the care and support of children; and the reputation and public aspects of the relationship.

Partners to an affair outside the established relationship are considered a couple and therefore when an affair ends the fallout will likely come with hefty financial obligations to the other person.”

Under Australian Family Law, partners to an affair outside the established relationship are considered a couple and therefore when an affair ends the fallout will likely come with hefty financial obligations to the other person, like any legal marriage or de facto relationship.

A case that came before the courts in Queensland tested this very situation.

It involved a wealthy, married businessman who’d been having an affair with a former female employee for 17 years. The couple had a sexual relationship, lived together for significant periods each year, and took regular holidays together. The man financially supported the woman but kept her existence a secret from his wife. When it all ended, the woman claimed she was entitled to a property settlement given they had shared so many aspects of their lives together.

In this case, her claim didn’t succeed – the fact they had never shared a permanent residence together and both kept their relationship secret influenced the court.

While each case involving extramarital affairs depends on its merits, if this couple had children together, the result may well have been very different.