Office romances are not limited to singles.
Office romances involve married male and single female.
Office romances involve married female and single male.
Office romances involve both genders, each may have a spouse.
There are the teacher student relationships.
There are the clergy, which we usually do not hear about.
It happens every where.

Michael,
Good point. I will take out that line about singles.
Might make for more interesting answers....

Never thought that work was a good place for establishing new romantic relationships. Just too much potential for problems down the road if things don't work out. Also, from the statistics presented, it appears that relatively few people find romantic partners at work: Only 15%, or about 1 in 7 couples meet at work. 6 in 7 meet elsewhere.

Offices romances also involve married men and gay men, gay men and married/unmarried women, three ways, sex with multiple office workers, and more.

Possible more unusual combinations...

The only men and women who will have difficulty going forward are of three types: predators (who suck), or chronic complainers who will bemoan the patrols of those mythical 'PC police', or those perpetual adolescents whose comments/compliments/actions betray a puerile ulterior motivation. If your compliment is really not about the dress, but the foundational anatomy, it shows (and you need to grow up).

Sorry fellas, no grown man has to act like a jerk. It's really not that hard to be simply civil, despite that incident you heard about from your buddy's neighbor's brother-in-law. And if you're in the latter group, yes - do be forewarned, lest you offend others and waste my managerial time investigating your leering fantasy life.

I dated colleagues in my checkered past, without incident - and I would again except I'm madly in love. The one smart rule discourages romances between bosses and subordinates. That's simply too fraught with disastrous potential - after all, how many of anybody's romances have really ended well enough that you should put the company's finances at-risk, in advance? Where I teach, there's a strict rule forbidding sexual contact between profs and their students. I tell 'em "ladies and gentlemen, you'll just Have to control yourselves." ;-)