The following excerpt explains what a work spouse is:
A work spouse is a co-worker of the opposite sex with whom you have a close platonic relationship. In many ways, these relationships can mirror a real marriage.
According to a 2007 survey from Vault.com, a career information Web site, 23 percent of workers reported that they had a work spouse.
Do you have a work spouse?
Here are seven clear signs you might have a work spouse:
1. You depend on a particular co-worker for office supplies, snacks and aspirin.
2. There are inside jokes that you and a specific co-worker share.
3. You can be bluntly honest with this person about his or her appearance, hygiene or hair (and vice versa). You're comfortable enough to point out that the other's hair is sticking up -- or that someone's fly is down.
4. When something eventful happens at work, this co-worker is the first person you seek out for a de-briefing.
5. At breakfast, lunch and coffee breaks, your closest co-worker knows what to order for you and how you like your coffee (and vice versa).
6. You and your co-worker can finish each other's sentences.
7. Someone in your office knows almost as much about your personal life as your best friend or real-life spouse does.
http://edition.cnn.com/2008/LIVING/worklife/11/10/cb.seven.signs.work.spouse/index.html