When Billie Quinlan and Anna Hushlak were described by Forbes as “the entrepreneurs who want to bring mindfulness to your sex life”, some readers of the business magazine may have been puzzled. A sexual wellness app? What would be the point?

Yet the pair firmly believed that there was a need for a myth-busting, educational and sensual guide to sex and intimacy that aimed to do for sex what Headspace did for mindfulness — and they were right. Since they launched the digital platform Ferly this year, after securing more than £1 million from leading venture-capital firms and investors, it has acquired users in 53 countries.

Users of the app, which is aimed at women, have been listening to podcasts about the clitoris, orgasms, the mechanics of libido, and the pros and cons of monogamy. Ferly also offers audio meditation courses, some of which encourage self-pleasure as part of the relaxation technique. There are intimacy exercises for couples and “sensual stories” too, helpfully rated from one chilli to five. In the spring the pair are moving from London to Los Angeles to build on the app’s success.

A need for a myth-busting, educational and sensual guide to sex and intimacy that aimed to do for sex what Headspace did for mindfulness.

Ferly is part of the latest booming health trend, sexual wellness. It may sound like the kind of niche interest you would find mentioned on Gwyneth Paltrow’s Goop website, but sexual wellness and mindful sex are fast becoming mainstream. Retailers such as Boots and Superdrug, along with the ecommerce sites Cult Beauty and Look Fantastic, have introduced sexual pleasure and wellness as a category on their websites. The overriding emphasis for retailers is on accessories rather than cheerily narrated mindful masturbation exercises. They sell toys and books to make sex more exciting — perhaps even a choreographed occasion, should you wish it to be so — with whoever you like to do it with, including yourself.

Hushlak, 31, originally from Canada, and Quinlan, 28, from Essex, met two years ago on a London business course designed to help tech start-ups. Ferly is an old English word, Hushlak says, used to describe things we don’t understand and find frightful — fairies, spirits, ghosts, witches. “Over the last few hundred years it has been reclaimed to describe something we don’t understand, but that inspires awe and wonder and marvel, so we thought it was a nice play on female sexuality.”

Their mission, she says, is to put sexual wellbeing “on a par with eating, sleeping, meditation and exercise, and recognising that it’s something we need throughout our lives”. The app was developed with the help of psychosexual therapists and by talking to hundreds of women (and 100 men).

Many experts believe that sexual wellness is the final frontier of good mental health. Kate Moyle, a psychosexual and relationship therapist, says: “Sexual wellness relates to the state of mental, physical and social wellbeing in relation to sex. A state of sexual wellness would be one where we make informed choices about the sexual experiences we want to have, as well as experiencing pleasure and enjoyment from sex, and feeling positive about the role of sexuality in our lives.”

The overriding emphasis for retailers is on accessories rather than cheerily narrated mindful masturbation exercises.

Far from being an indulgence, she says, it is fundamental to a healthy mind. “Sexuality is part of ourselves and our all-round health, both mental and physical. It’s just because it has been such a taboo subject for so long that historically sex has been treated as a separate entity, but as therapists we regularly see the link between sexual difficulties and mental health.”

So why is the idea of sexual self-care building momentum as a mainstream idea? Forbes notes that a few years ago investors would have been “squeamish” about this sort of venture. After all, it’s not so long ago that we were all mocking Goop and its enthusiastic endorsement of products such as Sex Dust (a “powdered aphrodisiac” that is now, incidentally, widely available).

Billie Quinlan and Anna Hushlak, co-founders of the Ferly

Alexia Inge, a co-founder of Cult Beauty, which launched its sexual pleasure and wellness range this year, says: “I wanted to normalise the sexual conversation, hopefully giving women confidence to be whatever sexual creature they fancy, if they fancy it. If people just want to buy a mascara and some shower gel, that’s also fantastic.”

Inge says that she wanted “to blow the dust off these ridiculous taboos”, as well as, presumably, sell a state-of-the-art, three-speed vibrator and a few bottles of Fur Oil, a “hard-working range for up top, down there and everywhere” and a bestseller on her site. “The commercial world has woken up to the fact that half the population has different wellbeing needs to the other, and, unsurprisingly, there’s gold in them there needs,” she says.

The global sexual wellness market accounted for more than £31.5 billion in 2017 and is expected to reach nearly £100 billion by 2026, according to Forbes. The market for “smart” sex toys or “teledildonics” (yes) is growing apace. The Lovely 2.0, a wearable ring, not for your finger, is a popular manifestation of this kind of technology. It has Desire-Sensing technology that connects to an app. During sex it monitors your body movements, can provide stimulation by vibrating, suggests positions to try next time and details how many calories were burnt — yours for about £110.

Boots launched its range online and in some stores with the slogan: “Sexual pleasure and wellbeing … at Boots? #NoReally.” It includes products by Smile Makers, a colourful collection of vibrators and lubricants, as well as So Divine accessories including the Vibrating Bullet (£7.99) and Sandalwood & Fig Massage Oil (£9.99), and Lovehoney’s Vibrating Love Ring (£9.99). “We’re really trying to normalise the conversation,” a Boots spokeswoman says, “because we know it is as important as any other part of your wellbeing, but people aren’t actually focusing on it.”

The market for “smart” sex toys or “teledildonics” (yes) is growing apace.

A survey for Boots last month — involving more than 2,000 women and 1,000 men of all age groups — found that while 80 per cent believe that sexual wellbeing can boost confidence and 60 per cent that it can improve general happiness, 80 per cent don’t feel comfortable talking about female sexual pleasure or intimate health.

Research suggests that our attitudes towards sex, particularly female sexual pleasure, may still need adjustment. “There’s a pleasure gap,” Quinlan says. “Men have more orgasms than women and that is problematic, and it’s because of the misunderstanding of the female experience.”

Moyle agrees: “Female sexual pleasure has historically been left out of the conversation. Although we are much more sexually liberal — there are orgasm classes, sex-toy shops — sexual anxiety is also at an all-time high.

“We only really ever talk about sex when we start having sex, around pregnancy and around menopause. It tends to be quite brief and functional.”

According to the Boots study, only 7 per cent prioritise sexual pleasure. How do we increase that figure? “We make the information accessible, we make it non-shaming, we normalise it,” Moyle says. Certainly, So Divine’s prosecco-flavoured lube (£7.99) and the Smile Makers Tennis Coach Vibrator (£39.90) sold by Boots are pitched perfectly for midlifers.

Sexual anxiety is also at an all-time high.

Indeed, although the Ferly app was launched with women aged 25-35 in mind, Hushlak believes that older groups also need guidance. “They can be struggling with their sexuality as much as the woman who’s going through her first break-up, or who comes from a culture where masturbation was never spoken about, who’s in a relationship where there’s no libido or intimacy any more,” she says.

There’s a paradox to our times, Moyle says. “We are still lacking good pleasure-based, relationship-based sex education, but we can google ‘sex’ and watch people have sex within a minute. Pornography has its place, but it was not designed as an educational tool.”

If porn is your first exposure to sex, she says, you may get a skewed idea of what sex is. Women may learn to think that their pleasure is irrelevant, men may suffer performance anxiety, and both are given the impression that connection and intimacy isn’t part of it.

Shopping in the sexual wellness aisle could become as noteworthy as buying toothpaste, according to the retailers. Boots’s analytics reveal that customers who bought a purple So Divine Magic Wand vibrator also bought Vicks First Defence nasal spray and Seven Seas Simply Timeless cod liver oil. “The products just come in an order with everything else,” Moyle says.

“It’s about recognising that it’s not a big deal to try something new. It doesn’t have to be intimidating to buy sex toys and gadgets. You can pick up your vitamins, and you can pick up a vibrator at the same time.”