'When it comes to determining whether or not your spouse is cheating, your intuition is the most powerful tool you possess,' the Sydney-based investigator said.
'If there's a receipt from a dinner for two at a nice restaurant, or an empty packet of condoms, these clues can give you a good indication of someone's activities.'
'There's no doubt most people are attached at the hip to their mobile phones these days, however if someone never leaves it out of their sight there's a good chance they are up to something.'
'If you share a bank account, sift through the statements for any purchases that stand out.
'Cheating partner will often need to purchase condoms, men are likely to buy Viagra and women a bottle of wine so items like these should stand out if you pay particular attention.'
'Most of us are creatures of habit,' Mr Athens said.
'So if you notice your partner is all of a sudden staying back late at work every night, or are scheduling social activities at all hours of the day, this is something to take note of.
'Also, if they don't ever invite you to join them, or claim to be swamped at work yet still arrive home cheerful and fresh, the odds are there is more going on than they're letting on.'