Every year, February builds up to that one holiday that means so much to so many: Presidents Day. What most people don't realize is that another day, hidden in the mix, promises love and joy to all whose hearts are pure and minds are dirty. We speak, of course, of Valentine's Day.

But what of those whose Valentine's expectations are disappointed with a gas-station bouquet of half-dead roses and an unsatisfying two minutes in the sack? It turns out disappointment and a need to feel appreciated leads many to stray after certain holidays, according to AshleyMadison.com founder Noel Biderman. Valentine's Day, New Year's and even Mother's Day spike traffic to the Web site for people looking to have an affair.

For your relationship to weather time and tide, you're going to need a guide. Here's our rough almanac to your year of marriage.