Your best friend lands a promotion – you smile on the outside while inside you seethe with jealousy. Sound familiar? Psychologists have dubbed it 'fr-envy' – friend envy – and as Melissa Field discovers, it can affect even your closest relationships.

As a daily commute to work, Natasha Welsh's journey is hard to beat. Not for her the sweaty bus ride or interminable traffic jam as she battles her way into the office. Instead, Natasha, 38, a Sydney-born, Bali-based fashion designer deposits her deliciously chubby-cheeked one-year-old son Matteo into the arms of his nanny. Then she pads barefoot past the pool, its aquamarine waters glittering in the sunlight, and upstairs to her tree-house-come-office, where she works until lunchtime.

Taking a break to steal a cuddle with her son, feed him and put him down for his afternoon nap, Natasha might then take a quick dip before returning to work on designs for her emergent clothing label Natasha.

If it sounds idyllic, it is – just ask Natasha's best friend, fashion designer Marie Hatzis. As the director of fashion label Hussy, Marie is hugely successful in her own right but admits to sometimes feeling pangs of envy. "Natasha's home/work/life set-up is perfect," says Marie, 35. "She lives in a beautiful villa that she works from too and is in a great relationship. Her gorgeous son is right there and she even has staff to prepare her lunch and do her washing and cleaning, so she can concentrate on her family and her business.

"She lives and works amid a real slice of heaven. Meanwhile, I work from nine until nine most days from a high-rise in Surry Hills and the view from my window is of the brick wall opposite. I admit it – I'm envious."

In fact, psychologists have a new label for this particular brand of envy – where we're thrilled for friends' successes but often, secretly, a bit jealous too. It's called 'frenvy' – and it's more widespread than any of us care to admit.

Frenvy can strike at any time, but common catalysts include a friend landing her dream job, effortlessly losing five kilos, announcing her engagement, or nabbing herself a fabulous designer top off the sale rail while all you could see was tat.

It's the little "why her and not me" voice you hear inside your head, even as you smile gamely and proclaim joy at her triumph. Or it's the niggling feeling, when a friend lands an amazing new job, that although you love your own career, the grass might be a little greener elsewhere. Usually, it's not insistent enough for you to end your friendship, but it can be loud enough to make you feel dissatisfied with your lot and, often, guilty for having uncharitable thoughts about a person you otherwise love.

But frenvy is often reciprocated – even if you think you're the only one feeling it, your friend might be suffering the same pangs, too. For example, while Marie is envious of Natalie's Bali-based lifestyle, Natalie admits to feeling jealous of the success of Marie's label, which is stocked in 80 boutiques and department stores around Australia, as well as from Hussy's three stores.

"Marie works really hard and I look at her and see a fantastic businesswoman, as well as someone who can totally switch on to her creative side when needs be," confides Natasha. "She's right across all aspects of her business in a way that I aspire to be but suspect I won't be able to match."

Read more about 'frenvy' and the how it affects friendships in the August issue of marie claire.

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