It's happened to an awful lot of us at one time or another: the shy smile in the lift, the sultry glance over the photocopier, maybe even the full-on embrace at the company Christmas party.
Given that most of us spend around a third of our lives working, it's hardly surprising that passion occasionally rears its head at the office. Indeed, according to online job site CareerBuilder.co.uk, nearly four in ten British workers have dated somebody at the same company, and 16 percent have done so more than once.
It can work out well. Of those who have dated someone at work, three in ten say they ended up marrying their office sweetheart. Others, though, have found themselves in trouble. According to AshleyMadison.com, ten percent of company Christmas party romances end in dismissal or disciplinary action.
In one high-profile case, Boeing chief executive Harry Stonecipher was forced to resign after an affair with a female colleague. Although an investigation concluded that the relationship was consensual and didn't affect the business, the board reckoned it was "inconsistent with Boeing's code of conduct."
All this may seem intrusive. But employers have a duty to their other staff to keep the working environment professional, says Juliette Franklin, senior solicitor for employment law at Slater & Gordon.
"It's a very fine line between interfering with these relationships and ensuring that you expect your staff to behave professionally, particularly if it affects your reputation - for example, if it's witnessed by clients or customers," she says.
"There's also the impact on other members of staff, in terms of whether it leaves them feeling uncomfortable if they're witnessing public displays of affection."
So what should you do if you and a colleague fall head over heels in love with each other?
While many office relationships do lead to happiness ever after, an awful lot don't - particularly those where one or both partners is married. And things can get quite difficult when a love affair comes to an end, but the ex-couple is forced to carry on working together. In the CareerBuilder survey, indeed, ten percent of workers said they'd had to leave a job because of a romance gone wrong.
Check company policy
As we've seen, some companies have a formal policy on office relationships. It's a good idea to abide by it, especially as it usually just means keeping things professional.
"Whether you are in an office or outside, when you fall for someone it just happens," says Scott Helmes, managing director of CareerBuilder UK. "If your valentine is in the office, remember to always keep it professional during business hours. Company policy doesn't have to be a romance killer, but always consult it first and make sure that your romance is not making your other co-workers uncomfortable."
Think before you go public
Most people eventually do go public about their relationship, but two in five don't. And as long as you're not breaking any company rules by doing so, there are good reasons to keep things quiet - at least at first. If the romance doesn't go the distance, it's much easier to return to a professional relationship with your ex if the rest of the office isn't watching avidly.
But don't count on keeping it secret
Sooner or later, most relationships come out. Forty-four per cent of people say that they've accidentally run into co-workers while out socially with their office sweetheart, for example. In the office itself, those knowing little glances may be a lot less subtle than you think they are.
All in all, it's probably best to just work on the assumption that people will work out what's going on before too long. And when they do, resist the temptation to lie - telling the truth will hopefully allay any concerns and help minimise gossip and rumour.