Being unfaithful in a marriage can be the most agonising trauma for anyone to endure.
No-one sets out to cheat in a relationship - but sadly, infidelity happens far too often.
Sexologist Dr Nikki Goldstein said nothing can 'affair-proof' your marriage because each infidelity is different - but there are things you can do to help prevent your husband or wife from straying.
Here, the relationship expert, from Sydney, offers her advice - and the tell-tale signs to look out for that could lead people to committing adultery.
Talk through your definitions of infidelity
Justify an affair to your partner to find out what exactly constitutes cheating.
'Talk about it,' Dr Goldstein told Daily Mail Australia.
'Ask each other "what's an affair? What's infidelity?" Some people might think flirting online with others is not cheating - but your partner might feel utterly deceived.
'Cheating doesn't mean penis in vagina. If you say you are going out for a drink with the girls but you are meeting a guy - that's deceitful.
'We all have a different definition to cheating but whatever the definition you take, if you're hiding something from your partner because you know it will hurt them, then you're being deceitful.
'If that's the case, take a hard look at your life and give yourself a swift kick reality check.'
She urged couples to sit down together and spell out exactly what behaviours are acceptable and what's unacceptable.
'Always address the issues - don't sweep your problems under the carpet. Always understand all relationships are not made to be perfect,' she said.
'If you're that person who thinks affairs would never happen to you - you're more at risk of having it so always communicate.
'Have that awkward conversation because it's the smartest way to avoid any affairs from happening.
'Ask each other "what could happen if one of us has an affair?" or "how would we feel if one of us cheated?" - you both need to understand the consequences.
'Look at what works best for us in our relationship. Are you having a healthy sex life? If you're not having enough sex, address what's going on in the bedroom. Not enough sex is actually an issue for some people.
'If you see that as a problem in your relationship, talk about it. Asking your partner why they're not having sex could hold the answer to your problems.'
'Not communicating can lead to affairs so be open, and ask each other "what do you think leads to affairs?" for you and your partner.'
Look at the red flags that could lead to cheating
'Ignoring the warning signs can lead to cheating so look at all the red flags for you and your partner,' she said.
'If you notice your partner pulling away from you or they feel disconnected in the relationship, talk about it with them.'
Dr Goldstein said other signs to look out for was any suspicious behaviour.
'Another sign is if your partner is hiding things like their laptop or phone, or if a charge on their credit card bill doesn't look right,' she said.
'Look at the opposite, someone could be overcompensating, lavishing you with dinners and gifts - and you think: "Hang on here, what's going on?"'
Trust your instinct
If you have been in a very strong marriage, you are much more likely to instinctively know something is wrong.
'Always trust your instinct,' she said.
'Far too often, women think "we're crazy, I'm just acting jealous or it's probably not true" - but if you know something doesn't add up, you need to speak to your partner about it.'
Be open about your temptations
'If you find yourself contemplating cheating or asking someone else out, put your hand up to your partner and admit you're having these temptations,' she said.
'Try and work out why you're tempted with your partner. If you're the partner who's recieving the statement, don't get angry.'
Dr Goldstein said it was important to be mindful that your partner has taken the first step to tell you about their thoughts before making any mistakes.
'For your partner to admit to their temptations, this just shows they truly want to stay with you so they are trying to work things out,' she said.
'Explore it rather than risk what could have happened.'
Affair-proof your marriage
Dr Goldstein said nothing will really affair-proof your marriage because each infidelity is different and you can't control your partner's thoughts or actions.
But with the right approach, you can strengthen your marriage and prevent any adultery from happening in the future.
'It's not a matter of preventing your partner from straying - it's a backward statement to keep men or women happy in the relationship,' she said.
'There's never a full-proof way to "affair-proof" your marriage but having that conversation is a start - and just be open about everything in your relationship.
'Both of you might think you don't need that conversation because neither of you believe you'd ever be in that situation.
'But you should talk about how you would both feel if one of you did find yourself in that situation because chances are, you're more at risk if you don't communicate.'