More than 1000 cheating Northlanders have signed up to a dating website designed especially for married or attached people.
The operators of European-based Victoria Milan claims it has 15,000 Kiwi members and 1020 registered as being from Northland.
The founder, Norwegian Sigurd Vedal, claimed the cheater's portal did not ruin marriages, but saved them.
He said the site helped people who were happily married, "but missing passion and adventure in their life", find a secret and discreet affair.
"Having an affair outside the relationship doesn't mean the marriage has to end ... we have actually saved hundreds, if not thousands, of marriages," he said.
He said around 73 per cent of site users only worked the site to flirt online before returning to their family and live their life happily, "boosted with happiness from the positive experience that flirting or an affair provides".
The site claims to be 100 per cent anonymous, featuring a "panic button" which members can use if partners walk into the room and catch their wandering eyes, and mouse.
According to the 2013 Census, 48.5 per cent of 151,692 Northlanders were married.
Mary Hodson, a sex therapist and spokesperson for Sex Therapy New Zealand, who used to work as a health professional at Kaitaia Hospital, said these websites brought out the worst in people. She doubted the site had 1020 members as the site had received negative reviews online.
"Their main objective is helping people to not get caught. This out of control sexual behaviour not only ruins the marriage, it destroys families.
"It's totally in conflict with what couples should be aiming for," which she said was emotional intimacy and trust.
She said out of control behaviour was often noted in people well before affairs, online or otherwise.
Ms Hodson also said an increase in technical gadgets and social media was resulting in couples becoming more disengaged. "This loss of emotional connection is detrimental. But before social media, TV distracted couples."
She disagreed with Vedal's claim that flirting online and having affairs saved marriages.
"If you as much as click on the site, you've gone too far."
She said many people had affairs because they were unwilling to become vulnerable with their partners about their own unhappiness in relationships. "They make a conscious decision to cross that line. It all boils down to the person's core beliefs and values.
"As hard as it might be, the best thing to do is to speak to your partner about the fact you feel tempted, trust them. That way, the affair will never happen."
She said while most couples chose to split up after infidelity, many couples did heal from such experiences.