Lynsie Lassig left a well-paying job she loved after a workplace friendship went sour.

And boy, did it ever. The ex-friend “made me feel like I could confide in her and really trust her,” Lassig says, but ended up using personal information told in confidence as grist for office gossip and taunts. A supervisor told Lassig to ignore the behavior, which grew so hostile that she quit.

Lassig, a medical billing specialist in Sandy, Utah, is satisfied with her new job. However, the effects of the workplace mishap linger. “I no longer trust people I work with on a personal level, and I certainly won’t spend time with them outside of work,” she says. “I don’t discuss my personal life at work on any more than a superficial level. I refuse to be friends with co-workers on Facebook.

“Work is every man for himself, and I am looking out for myself from now on.”

Perhaps Lassig was smart to establish boundaries at her new job, but it’s possible that she overcorrected.

Employees who are least willing to develop workplace relationships also seem to be the least likely to be promoted, according to Shawn Achor, author of “The Happiness Advantage: The Seven Principles of Positive Psychology That Fuel Success and Performance at Work” (Crown Business, 2010).

Building on research for the book, Achor divided employees he studied according to the extent to which they developed work relationships and provided support to colleagues. Just 5 percent of the bottom quartile – the relationship avoiders – were extremely engaged in their work, and just 7 percent had been promoted in the past year. About 40 percent of employees in the other quartiles received promotions, Achor reported in a July blog post on the Harvard Business Review website.

Better relationships with colleagues are associated with workplace success. “Social support does not mean that you are designated as friends,” Achor clarifies. “It means that you can rely on the person, you share resources, you work interdependently to accomplish mutual goals.

“Social support is about the quality of the relationship, not the nature of the relationship.”

Gestures of social support that Achor asked subjects about include helping people at work when they fall behind; fostering conviviality by bringing in food or arranging a coffee break or birthday party; and inviting coworkers to connect outside of work for “socially appropriate” lunches or drinks.

“What is appropriate for peers can be different from what is appropriate with your manager,” Achor says, “but both can be high-quality relationships based upon knowledge of each other and shared goals.”

Giving off warm fuzzies instead of cold pricklies at work can contribute to career success and advancement because “people tend to like you more if they feel close to you and liked by you,” agrees psychotherapist and workplace wellness trainer Judy Belmont of Allentown, Pa. “When you touch people’s emotions, they tend to want to be on your side and help you out. I’m not saying you have to be best buddies with someone. Just be empathetic and accessible, rather than cold and distant.”

Poor relationships at work cost U.S. companies billions annually, Achor says. “I know of countless workers who stay at companies when they are getting better offers elsewhere just because they value and like the people they work with. I’ve also seen people leave well-paying jobs just to have the opportunity to find people they actually like working with.”

That’s what Lassig did. Achor hopes his findings “give isolators good reason to rethink their reluctance to reach out.”

Lassig, who feels she was targeted in the first place because she is “soft-hearted,” says she is reaching out but not testing boundaries. “I have been able to open up to people more at my current job, but I am careful about how much personal information I share with them, and I am cautious of who I associate with. If someone seems like trouble, I stay far away.”