(LifeWire) -- After two years of backbiting, former best friends forever Paris Hilton and Nicole Richie returned to back scratching -- just in time to promote another season of their reality television show, "The Simple Life."
The friendship of Nicole Richie and Paris Hilton has had its ups and downs.
Former friends and roommates Lauren Conrad and Heidi Montag, however, remained estranged as "The Hills" began its third season in August.
At its height, the showdown between Montag and her Machiavellian boyfriend Spencer Pratt and fan-favorite "L.C." threatened to overwhelm the reality show.
These two love-hate, friend-enemy relationships are high-profile examples of the "frenemy" phenomenon.
The term has most often been used to describe females who tangle with their female friends. And this notion, says Terri Apter, co-author of "Best Friends: The Pleasures and Perils of Girls' and Women's Friendships," isn't that far off the mark.
Females are more competitive with their friends than men due to cultural circumstance, Apter theorizes. "They (women) sometimes idealize their friendships -- they should only be loving and supportive -- whereas the wider culture allows men to enact the inevitable competitive feelings openly, without feeling ashamed or guilty," she says.
Every friendship -- no matter how solid or tentative -- has mixed feelings of support and antagonism. Apter says that "among female friends there is also something else: a wish to offer support and see a friend thrive, on the one hand, and a fear of being left behind or out-shone, on the other." In essence, the "hate" part of a love-hate relationship isn't really hate -- it's envy or insecurity.
Maria Calderon-Saban, 23, knows what it's like to be in a frenemy situation. While in college, Calderon-Saban said one of her friends had an affair with Calderon-Saban's on-again-off-again boyfriend.
Tears and much arguing ensued, but Calderon-Saban ended up forgiving her friend. In fact, "we still hung out pretty often because we had mutual friends," says Calderon-Saban, now a marketing assistant in Honolulu, Hawaii. When they went their separate ways, "we kept in touch, but that faded fast, mostly my doing," said Calderon-Saban. "I just lost all will to continue the friendship."
Not all frenemy situations end after the first big blow-up, though. Jeani Hunt's long-term friendship epitomizes the fight-forgiveness cycle. Despite the problems, Hunt still considers the person in question a good friend.
"When she and I get into a certain mood, we will be laughing all night," says Hunt, 23, a public relations account coordinator in San Francisco. However, what she calls her friend's habit of mocking has chipped away at their relationship. Once, Hunt lost a pair of house keys when she went on a run, and the friend began teasing her. When history repeated itself, "she just kept bringing it up to show how retarded I was," Hunt remembers.
So why do women put up with fair-weather friends? The reason is simple: If a woman has invested a lot in the relationship, she is likely to work to salvage the relationship, despite the rocky moments, says Jan Yager, a relationship coach in Stamford, Connecticut, and author of "When Friendship Hurts: How to Deal with Friends Who Betray, Abandon, or Wound You."
"Males, having a much lower threshold for complications in friendships, will disengage themselves from a negative friendship more easily, and faster, than the typical woman," Yager says.
How to salvage a love-hate relationship
Yager outlines five steps for salvaging the good in a love-hate friendship:
1. Don't make things worse. If your friend's nastiness only surfaces at certain times (for example, when she is stressed), try to avoid her at those times; you don't always have to make yourself available. When she antagonizes you, consider defending yourself, but tactfully so as to avoid adding fuel to the fire.
2. Keep a support system. "Make sure you have, or that you cultivate, other friends who are consistently positive and loving so you can remind yourself that a friendship doesn't have to be a love-hate relationship," advises Yager.
3. Focus on the good. "If you really want to keep the love-hate friendship going, make sure you remind yourself of the traits about your friend that are loving and why you want to keep the friendship going, dwelling on the positive rather than the negative," says Yager.
4. It's your friend's problem. Even when confronting your friend, don't follow in her negative footsteps. Don't consider this situation to be your fault or let it lower your self esteem.
5. Don't let her get to you. Above all, don't let your friend drag you down. Instead, "maintain the positive, loving personality that you have despite her temporary or longstanding love-hate behavior," says Yager. E-mail to a friend
LifeWire provides original and syndicated lifestyle content to Web publishers. Jocelyn Voo is a freelance journalist and relationships editor at the New York Post.
All About Nicole Richie • Paris Hilton