Polyamory: Vaults' lead singer Blythe Pepino and her partner reveal why monogamy wasn't doing it for them

I meet Blythe and Tom in a bar in Clapham. Blythe's pastel-pink hair is easy to spot from a distance. Slim, sandy-haired Tom sits beside her. As I approach, their heads are together and they're giggling softly. They look every inch the loved-up couple. I introduce myself and slide on to the sofa next to them, hoping three won't be a crowd. I needn't have worried.

The pair have been polyamorous from the beginning of their relationship after both realising, separately, that monogamy wasn't doing it for them. Polyamory is an umbrella term for intimate relationships that involve more than two people. The expression covers everything from swinging to triad relationships. Typically, these encounters involve sex, although it's not a prerequisite.

The dating website OkCupid recently became the first dating site to add a "polyamory" function for its users, allowing already established couples to search the site for people to join their relationships. The feature will also be available to singletons looking for open relationships to join.

The lead singer of the British band Vaults, Blythe Pepino, 29, and her partner, Tom Jacob, 27, agree to meet me to shed some light on what it's like to be non-monogamous. The couple dissolves into giggles when I ask if they've had time to prepare for our interview. Exchanging knowing looks, they tell me they tried to do some planning that afternoon but got "distracted". Cue more titters.

They have been an item for two years and live together in south London. Blythe also has a girlfriend, Alice, whom she's been with for over a year. Alice – an artist – lives in Bristol, so they don't get to see each other that often. Tom is seeing another girl, Sian, whom he met on Tinder. In addition to this, Tom and Blythe recently started dating a couple, Nich and Sonya, whom they met at a specialist club night in London. Blythe tells me they "fell in love with them as a couple" and now hang out regularly. Sometimes they go to the movies, sometimes they have group sex. Blythe and Tom also have one-night stands with people, although these happen less frequently. "I'm just not that good at them," Tom says.

A common misconception, they tell me right off the bat, is that people in polyamorous relationships don't get jealous. That, apparently, is not the case at all. In fact, both Tom and Blythe readily admit to having experienced feelings of jealousy at some stage in their relationship. The trick, they say, lies is how they deal with that emotion. Namely, through talking. Open and honest communication is essential to polyamory. Blythe and Tom tell me that whenever one of them sleeps with someone new, they schedule a meeting the following day to discuss what the latest tryst means for their relationship.

"When we started, we had one rule, which was that we'd always talk about it," Tom says. "If one of us had been with someone else, we'd put a bit of time aside the next day."

My eyes must widen at this point because they start to chuckle again. It all seems so well-organised. I'd imagined multiple-partner relationships to be driven by red-blooded lust and a desire to sleep with as many people as possible, but Blythe and Tom's account suggests there's quite a lot of admin involved, too. "It would be very disingenuous if I said it wasn't a lot of work," says Tom. "But it's so worth it."

OkCupid made "open relationship" and "non-monogamous" relationship status options back in 2014, but this is the first time the website has allowed couples to actively search for partners. The new feature comes after the site noticed an increased interest in polyamory over the past five years. When asked in 2010 whether they would consider dating someone who was already involved in an open or polyamorous relationship, 42 per cent of all OkCupid users said yes. When asked the same question in 2015, half of users said yes.

"Finding the right partner is extremely important. Hence, users should have the option to best describe who they are and who they are searching for," OkCupid's chief product officer, Jimena Almendares, says. "We identified a trend towards more openness, and even curiosity, regarding non-monogamous and open relationships."

According to the Relate counsellor and sex therapist Peter Saddington, polyamory is becoming more common simply because people are being more open about the way they conduct their relationships. "To some extent there may be some links to thinking about gay and lesbian communities," he says. "It's always gone on and as it's become more acceptable and more recognised, more people talk about it."

Although he doesn't accept that people are becoming disillusioned with monogamy, Saddington does think children's upbringings could impact their future relationships. "Lots of children grow up in families where parents separate," he says. "I suspect some of that is starting to have an impact on how children, when they grow up, perceive relationships."

In fact, Blythe tells me that her desire for a polyamorous relationship did stem from disillusionment with more traditional relationships, of which she's had a few. "I kept having relationships where there was not enough trust or communication," she says. "So it kind of was born out of a need to start having relationships that were totally fearless or aware of one's fears."

Blythe and Tom inch closer to one another on the sofa as the interview progresses. Every now and then they reach out and touch each other, threading their fingers together as we talk. It's obvious they're extremely close and I don't doubt their commitment to one another. At one stage, when Tom self-deprecatingly describes himself as a skinny little blond boy, Blythe grabs his hand and cries: "I like you skinny!"

We talk about children, too. Although they're not sure yet that they want a family, Blythe says she can't think of a better person to be a father than Tom. "I mean, the way you fill the dishwasher is just incredible, so precise," she says, laughing and quickly dispelling the myth that polyamory is all about seduction. Tom says he's sure that parenthood and polyamory would work together.

Incidentally, both sets of parents are fully aware of the couple's non-traditional situation and are very open-minded about it. Tom says he thinks his mum always thought he was gay so polyamorous was a "curveball".

But when I ask the pair whether they would use a dating site like OkCupid to invite other people into their network, they're unsure. Tom thinks they wouldn't. "In general, we prefer these things to happen naturally of their own accord," he says. Blythe agrees but says she can see how a website like OkCupid might be helpful if you wanted to make your relationship status obvious from the off. They both think polyamory is becoming more common.

Do they plan to be in a polyamorous relationship for ever? Although they're typically open-minded about the future, they have no immediate plans to change. Tom says: "At the moment what I'm doing now is just too good."