Sadness Is Contagious, But Don't Worry: That Case of the Discontents Will Only Last You Five Years or So
Not only is divorce potentially contagious, so are feelings. Which explains why when you're around someone who bitches and moans all the time, you want to start bitching and moaning (probably about them), too! Sadness begets sadness, and happiness brings on more happy. (We're happy it's Friday, how 'bout you?)
Hang in there for a few more years, Chris.
According to the L.A. Times, researchers at Harvard University and MIT have discovered that an individual's emotional state is linked to the emotional states of their friends. Meaning, you can "catch" happiness, sadness, or whatever other emotion you (or your pals) might feel. Why do you think those emo kids all stick together? Of course, there may be a chicken/egg thing going on with this...
At any rate, sadness is more contagious than happiness -- having one friend who is blue doubles your chances of getting sucked down into the dumps as well, while a happy friend only increases your happiness quotient by 11 percent.
However, the "recovery time" from your bout with the happies/sads doesn't depend on your friends, and the good news is, happiness lasts longer.
People were found to "recover" (return to neutral) more quickly from discontent than from content; on average, a contentedness "infection" sticks around for 10 years, but it takes only five years to recover from discontent.
(FYI: This refers to longer periods of sustained emotional states, not just those laughing fits that knock you off your chair now and again.)
Of course, you can also get happy or sad based on events in your own life, which is good, because sometimes you just want to enjoy yourself and your Friday night without your friends bringing you down 'cause they got fired or dumped or whatever (our friends are so self-absorbed sometimes!).