When was the last time you texted your ex? Maybe you're on good terms and remained friends after the relationship. Or, you were looking for a little ego boost from someone you know is still hung up on you.

There's nothing fundamentally wrong with this behaviour between consenting adults. But throw a new relationship into the mix, and that's when things can get complicated.

Social media, Whatsapp, and dating apps have muddied the waters of modern dating, and the line of what constitutes as cheating is blurred.

Ashley Madison, the dating site where people go to cheat on their partners, has gathered some data from over 3,000 users on what they believe to be unfaithful behaviour, except for actually having sex with someone else.

Among them are spending time with an ex, and sending explicit messages to someone else. But it's the emotional affair behaviour that came out on top.

"People make a conscious choice to cheat, it's not typically something that people fall into," said Tammy Nelson, a sex and relationship therapist.

"Despite defining what infidelity means to one another, one or both people in a relationship could still make the choice to seek an extra-marital affair when their needs aren't being met. An alternative conversation to have is one that outlines what it is that each partner needs from the other to feel happy and satisfied in the relationship, and how to talk about it when they don't feel that."

Here are the 10 behaviours that count as cheating, ranked in ascending order by the percentage of Ashley Madison users who listed them: