And in this, Millennials realize that they’re pushing the boundaries of the sexual revolution beyond what their parents might have expected and their grandparents could even conceive.

In fact, Leah and Ryan are noticing a trend that’s been on the radar of therapists and psychologists for several years now.

Termed “The New Monogamy” in the journal it’s a type of polyamory in which the goal is to have one long-standing relationship and a willingness to openly acknowledge that the long-standing relationship might not meet each partner’s emotional and sexual needs for all time.

“I like everyone to meet each other and be friends and stuff,” he explains.

"There was a side of me that was ecstatic – the teenage boy in me that wants to fuck everything I see," reveals Ryan, a millennial in an open relationship.

Tonight is one of those nights, and soon Leah will head to Jim’s penthouse apartment, where the rest of the evening, she says, will probably entail “hanging out, watching something, having sex.” “She’ll usually spend the night,” Ryan adds nonchalantly, which gives him a chance to enjoy some time alone or even invite another woman over.

He doesn’t have a long-standing secondary relationship like Leah (“I’ve actually veered away from doing that”), but he certainly enjoys the company of other women, even sometimes when Leah is home.

Or, more specifically, that going outside the partnership for sex does not necessitate a forfeiture of it.

“I was at a practice where we would meet every week, six to eight therapists in a room for teaching purposes and to bring up new things coming into therapy that weren’t there before,” says Lair Torrent, a New York-based marriage and family therapist.

Because they started off dating long-distance (Ryan was living in Colorado at the time), it was understood that they would not be exclusive: They initiated a policy Leah describes as “don’t ask, don’t tell.” But when Ryan moved to New York and began living with Leah a year and a half later, he assumed they would transition immediately into monogamy.

“I thought, ‘All right, the long-distance shenanigans are over now, we’re moving in together, and it’s time to have a real go at this,’” he says, taking a sip of his beer.

I have couples that have closed relationships or open relationships depending on how they feel about the relative health of their relationship.