While men are more likely to be away at "urgent" meetings or show less interest in sex, women are more devious in their infidelity and often recruit their friends to cover for their deception.
Private investigator Kerrie Pihema said that while Valentine's Day was often about chocolates, cards, nice dinners and jewellery, it was also the "most opportune time of the year" ahead of the Wellington sevens or the office Christmas party to bust cheating partners.
A former police officer who now delves into relationship infidelities, Ms Pihema said last-minute work meetings, a flurry of texting, "cyber cruising", taking cellphone calls in other rooms, cash withdrawals and unexplained purchases could all be seen as red flags.
"These people who are cheating will often be busier on February 13 trying to juggle both their lovers and significant others," she said.
"It's that time of year when the infidelity chameleons really come out."
Ms Pihema said that while there were some common cheating denominators men and women shared, the tell-tale signs were often quite different.
"For men, they're often away at unexplained times, there's less sex in the relationship and they will criticise more and be more confrontational.
"But women are a lot more innovative and cunning and we have found they will often involve their friends in their deception."
Ms Pihema said nearly 80 per cent of the cases she investigated involved work colleagues.
SIGNS OF A CHEAT
* Urgent, out-of-town meetings.
* Excessive texting or time spent online.
* Two cellphones.
* Taking calls in other rooms.
* More time spent at work.
* Less interest in sex.
* Unexplained purchases or cash withdrawals.
Source: Rokez investigations