When Angela and Bradford met for the first time and subsequently started dating, there was a big condition for their relationship to work.
It had to be open.
Both coming out of marriages, the pair didn't want to fall back in to a "normal" relationship.
"Monogamy didn't work for us," Bradford, 39, told news.com.au.
"Nether of us would ever go back to it.
"We were both married before meeting one another, which weren't open relationships," Angela, 38, added.
"When we started dating, we were hooking up and it wasn't serious. But when we wanted it to be more serious, we made it known to each other that we wanted to see other people.
"This quickly turned in to seeing couples together ... we call it friends with benefits."
The pair, who now live in Sydney and run adult sexual education classes in addition to their full time jobs, said every open relationship was different - but they tend to see other couples together.
"It's a fun experience, but the key to any successful open relationship is a strong basis of communication and trust," Mr Atom said.
"There are times when we see people separately, which we talk about in depth. This is much more than just sex.
"We consider ourselves 'socio-sexuals', meaning we like to have a deeper relationship with people and not just sex.
"Sometimes we have sex sometimes we don't," Mrs Atom added.
"Sometimes we might just have a drink with someone, or go to dinner. It's not just a wham bam thank you ma'am."
While Mr and Mrs Atom would never go back to a monogamous relationship, they do acknowledge jealousy can come in to play from time to time.
"We are each other's home base, so no matter what happens or who we see, we will always come home to each other," Mr Atom said.
"There is no one that will interrupt us, but jealousy can come in to play.
"But there's two sides to the coin with jealousy. Compersion on one side, which means you're happy if your partner is happy, and on the other side is jealousy.
"For us, it's about getting in check and in balance.
"We understand this is fringe," Mrs Atom added.
"We are not the cookie cutter mould of normal. But everybody is very supportive of us."
Mr and Mrs Atom saw a gap in the adult sexual education market, and made the decision 18 months ago to launchBy the Bi - which teaches couples and singles everything they've wanted to know about sex, but haven't felt confident or comfortable enough to ask.
"A lot of people in the 25 to 50 year old age group get their sexual education from porn," Mr Atom said.
"That's like getting life information from an Avengers movie. So we wanted to educate adults to have a better relationship with their partner."
The classes, which run once a month from a club in Sydney called Our Secret Spot, starts off with a presentation before concluding with a live demonstration. The Atoms say they demonstrate massage techniques but not sex.
"This is so people can see and understand what has been spoken about at the start of the class," Mrs Atom said. Then participants in the class can go home and try it for themselves.
Angela and Bradford will be holding a Swinging 101 class as well as "The Art of Flirting" demonstration at Sexpo in Melbourne from November 16 to 19. For more information, check out sexpo.com.au