The key advantages to not having a girlfriend at Valentine’s Day: it’s quite a bit cheaper, and nobody can complain that you’re spending the evening working on job applications and finishing the Veronica Mars Season 1 DVD set.
The key disadvantage: you can’t email any female colleagues (particularly ones from the vaguely-recalled distant past) to ask for favors relating to said job applications because they might think you might be hitting on them on Valentine’s Day.