But they exchanged a few texts, then graduated to friendly lunches.
Eventually Matt asked Sarah on a date, and they talked for so long that the sushi restaurant had to kick them out.
"I did not ask, and I spent the next six months wondering if every work email he sent was a subtle invitation to get at it again," says Mia, 30, a management consultant in New York.
"None were, and my work life would've been better if I'd known that."__Don't Flirt (Too Much) __If you do decide to start a relationship, remember that others will probably pick up on the sparks.
If you ask repeatedly, says Green, you risk creating a hostile work environment for your crush, which can be defined as harassment.
And if a colleague asks you out and won't take no for an answer, that may be harassment, and you should consider talking to HR. If you make out with someone at the holiday party, bite the bullet and ask about the person's intentions afterward.
But their co-working is going smoothly as a result.
Sarah, a 30-year-old graphic designer, met Matt through a colleague at the imaging tech company where they both worked.
"I didn't really notice him at first because he had a beard, and beards weren't my thing," she says.
Jessica, 25, an antiques expert who moved across the country and, basically, in with a coworker, eventually realized that the relationship-job combo was dominating her new life.
"I hadn't made any female friends, and I missed that," she recalls.