When it comes to female friendships, finding a good balance is vital, psychologists say. But what about the female friendship that suddenly turns sour? Call it unhealthy female competition, moments of envy, or just spending too much time with one person, the female relationship can become complicated. And when it does, it can also turn destructive. So, what are the warning signs of a friendship going bad and what should we do when the cracks start to show? Susan, 30, had been friends with Nikki since college. They shared the same friends and even the same career. 'Nikki was always incredibly needy and self-absorbed,' says Susan, a real estate agent. 'The friendship was becoming toxic. She was always talking about herself, but when it came my turn to share, she wasn't interested. 'I started to become physically and mentally drained every time I saw her. She would get annoyed if she found out I was seeing other friends instead of her.' When Susan's career and love life surged ahead, Nikki became even nastier. 'I needed to get away,' Susan says. Emma, 39, also learned the hard way. She met Jane through a mutual friend and discovered that they had much in common. They started spending a lot of time together. 'It felt safe to share my life with Jane,' Emma says. But the cracks soon became evident for Emma, a public relations professional, when her interests suddenly became Jane's too. 'She developed a sudden interest in the same clothing, music and even friends,' Emma says. Cathy Tsang-Feign, a Hong Kong-based psychotherapist, says there are definite warning signs in this kind of friendship. 'The person asks a lot of questions,' she says. 'She's overly interested in you, treating you like a celebrity.' Rachel, a 34-year-old stylist, remembers getting an unsettling feeling after only a few months of being friends with Caroline. 'She picked up my mannerisms and interests, as if she thought I was great,' Rachel says. 'I knew the friendship wasn't right when she started asking too many questions about my boyfriend.' 'When relationships cross the line and become incestuous that's unhealthy,' Tsang-Feign says. 'You need to collect yourself and get back stability and balance, regain your identity and tune into self-care.' Hong Kong-based clinical hypnotherapist Kitty Sak says that matters get worse when one woman allows the other to invade her personal space. Rachel feels that she may have done this. 'Not only was Caroline intrigued with me; she was also overly intrigued with my boyfriend and other friends of mine.' Things got worse when her boyfriend accepted Caroline's offer of a room in her flat when he needed a place to live. 'I knew the friendship had to end. I broke up with my boyfriend and got away from her very quickly.' Sak advises walking away from this type of friendship. Tsang-Feign suggests setting the boundaries early on. 'Try saying things like, 'I need to refocus on myself over the next couple of weeks. I'll be very busy'. Make a nice excuse and pull back,' she says. It doesn't have to be dramatic. When Nikki went backpacking around Europe for nine months it was a convenient time for Susan to ease out of the friendship. 'It was hard to keep in touch as she was moving around, so I didn't write.' Two months after Nikki returned 'she wrote me a letter saying how angry she was that when I came to meet her at the airport I told all her friends that I was engaged. She basically accused me of 'stealing' the limelight from her,' says Susan. Maya, 52, also regrets not seeing the warning signs in her 11-year friendship with Jun. Both worked in the garment industry. When they met, Jun had one close female friend, but she soon dropped the woman to devote her time to Maya. 'I noticed this but thought nothing of it,' says Maya. A year later Maya and her husband went into business with Jun, but a month later Maya's husband said he couldn't work with Jun. 'He said she was controlling.' 'Normal women don't feel jealous of their friends,' says Patricia Evans, American psychologist and author of Controlling People: How to Recognise, Understand and Deal with People who Try to Control You. 'Most women recognise non-normal people - for instance, narcissists who want the world to revolve around them and don't try to maintain friendships with them.' Evans says to be wary of situations in which one person is telling another what to do. 'A friend who tells you what to do, how to do what you do, and what you should do is merged into you, and acting as if she were you and knows what you should do,' she says. 'I can see now that I was letting Jun control me,' says Maya. She stayed in business with Jun, but built boundaries to protect herself. A friendship is like a love affair: both people have to want to be in it. Tsang-Feign says that 'any relationship has to have healthy boundaries'. She stresses the importance of being able to put limits on the amount of time spent with another person. 'If a bad friendship does come about, it's usually because someone is needy and you may require that person to be needy,' she says. Tsang-Feign suggests pulling back. It's impossible to control a friend. One thing that can sour friendships is how much is shared. 'When a relationship becomes public domain it hurts a friendship,' she says. Emma tried to cope with Jane's behaviour by keeping her thoughts to herself where she'd previously been open and honest. Psychologists say there are many reasons for the souring of a friendship. They can include anger, competitiveness, jealousy and envy. The late Austrian psychoanalyst, Melanie Klein, in Envy and Gratitude defines envy as 'that angry feeling that another person possesses and enjoys something desirable - the envious impulse being to take it away or spoil it.' Envy and jealousy aren't interchangeable and yet are often confused. Jealousy concerns a relationship between three people. Envy only needs one other person for it to occur. Put simply: A wants what B or C have. In Rachel's case, Caroline was consumed with envy. 'Caroline had become so fixated on getting whatever I had she even ended up living with my boyfriend,' says Rachel. Jan Yager, author of When Friendship Hurts: How to Deal with Friends Who Betray, Abandon or Wound You, says if these feelings are not dealt with they can turn to rage. Emma says she did try to confront the issue, but ended up feeling betrayed and manipulated. 'It took me a long time to feel I should accept what I cannot change and move on from the friendship.' A good friendship is built on mutual trust and common interests. Both men and women benefit from the support and understanding a good friendship gives them. The right friendship won't suffer from the negativity that feelings such as envy and competitiveness can bring to a relationship that has problems. Healthy friendships are 'mutually respectful, have clearly set boundaries and involve someone whose company you enjoy', says Tsang-Feign. A good, mutually supportive female friendship far outweighs the rare experience of a destructive relationship.