And even if your married co-worker is the slap dick and you're the responsible one, the perception still may not change. From your boss's perspective, that guy's money is going toward feeding his kids. Yours could be going toward any number of elicit activities he's vaguely aware of. One of those sex parties he's seen on those HBO documentaries, perhaps.
Single People Tell Themselves:
In an unprecedented act of kindness, American corporations decided their employees were working too hard and began enforcing something called "work/life balance." Of course they had their selfish reasons. A happier employee will do better work, and get sick less. But who cares? Less work means more time for us single folk to go out and have indiscriminate sex with one another, right?
If you're single, work/life balance is yet another way for the world to punish you for being unloved. One way the "balance" is enforced is the Family and Medical Leave Act, which gives any employee the right to take time off if a spouse, child or parent gets sick.
But what if you're struggling to save up enough money for a ring for your girlfriend of seven years when she gets hit by a bus? According to work/life balance, you'd better have some vacation time saved up. Otherwise, you're just going to have to learn to weep a little quieter, because you're sort of bumming out the rest of the folks in Accounts Receivable.
Take it outside.
There's also the unofficial considerations. Married employees simply have more legitimate excuses to ask for time off: a kid's birthday party, an anniversary dinner, Christmas. Yes, single people are more likely to be asked to work on holidays. The logic goes: You're single, you don't have a wife or kids, what could you possibly have to do? It doesn't matter if you were planning to spend the day delivering presents to sick children. Someone's got to pick up the slack for the married guy who keeps taking time off to attend his daughter's dance recital.