Some blame it on the man drought, others say all the good ones are taken, but often singles are just self-sabotaging, psychologist John Aiken says.
"It's a good idea for singles to be thinking about how they contribute to the situation," the Australian author and relationship guru said. Aiken penned the book, Accidentally Single, to give lonely hearts a "wake-up call about the way they sabotage themselves in the dating game".
"I wanted people to sort of take some ownership and say, `look at yourself here'," the 39-year-old said while visiting Auckland. He writes about the 15 most common mistakes his clients appear to be making in their quest for love.
Top of the list is falling for people they can't have.
"They're not going to give you what you want," said Aiken, who spent 20 years living in New Zealand but recently moved to Sydney with his wife. "You might date, you might have some great sex, but at the end of the day, it's not going to go any further."
The "unavailable types" might already be taken, are travellers, flirty or work focused, and just not ready to be tied down, he writes.
But Aiken is quick to add, there is nothing wrong with being unavailable yourself.
"If ... you're happy to put work, friends, family, travel and money first in your life, read no further. This book's not aimed at you," he writes in the introduction.
Aiken, who has been a practising psychologist for 15 years, said people in their 20s are usually happy to be free agents.
"Those people that are looking to be single, happy being single, will be putting up these barriers and they won't have any real drive to change them. The trouble you get into is when you are looking for someone to settle down with ... and unknowingly you're continuing to put up barriers. It's when you get to your 30s and you start to see people settling down and you're finding yourself struggling to do that that you become aware of these patterns," he said.
"They are patterns that they've got in to without awareness that they've just kept repeating. Other "patterns" Aiken includes in the book are being hung up on past relationships, being too clingy and only being into casual sex. It's those sort of mind sets that generally shut you down in the game," he said. "It's important that you become aware of these if you're going to meet the right partner."
Aiken said his experience in Australia and New Zealand indicates people are happiest when they're happily hooked up.
"When people are in happy relationships ... they will find life going much easier. They've got the support network there, a companion, they've got the intimacy and the affection ... to be there during times of crisis.
* Accidentally Single, by John Aiken, published by Penguin, is available now. RRP $30.
By Nicky Park - AAP