Monogamy is one of those rare anomalies in the animal kingdom. In most species animals are just like, "hey, you're pretty," or "you build an awesome nest," or "I'm in heeeeeeeeeat, gahhhhhhh," and they make babies and carry on. A few species are monogamous and mate for life, but most aren't. Humans have pretty much the same instincts. Some tend to be "wired" for monogamy, others aren't. The big difference between humans and other animals is that humans are obsessed with rules. There are millions of written and unwritten rules on how humans are supposed to behave, and they all vary depending on culture, religion, who raised you, etc. Many of the rules make sense from a survival standpoint, but a lot of them are just mind-bogglingly ridiculous. I mean, people fuss over stupid trivial rules all the time, like where to put the salad fork or what time the kids should go to bed. It's hard to tell if a person is wired one way or another, because most cultures have rules that basically say, "you must find a mate, and you must marry this mate and make babies, and if you even THINK about finding another mate, you're a horrible person and the flames of hell will tickle your soul and booga booga booga!"
Now, I can understand the benefits of monogamy from a baby-making standpoint. If you're attached to one person, you know which guy is the father of your baby (although humans have reaped the benefits of scientific rules, and DNA tests can also prove this), and if the guy is a decent sort, he'll stick around and help care for the baby. (If the guy doesn't stick around, you fail at finding a decent mate. Try to find someone who isn't a douche next time, ok?) It's also good for preventing most cases of STDs, because STDs generally result from careless acts. (If you sleep around and/or don't use protection, you're just asking for trouble.) I can also understand that if two people who are "wired" for monogamy get together and are compatible and satisfied with each other, things can work out great.
But I disagree with the societal rule that you "have" to be monogamous. I understand that there are a billion complications with interpersonal relationships or whatever, but that's because humans have their silly social rules and have some sort of need to make everything as complicated as possible. (Seriously, does it really matter if you wear green socks with a red tie? Did anyone ever die from putting their elbows on the table? Does God really kill a kitten every time you masturbate?) Humans also generally suck at interpersonal relationships. They fight over stupid things like chores and money and whether to get Chinese or Mexican food. Fighting over mates is just another thing animals do, whether they're monogamous or not. Humans just make their fights more complicated.
I say screw society (not literally - that would be very painful, and you'll get every disease ever). Do what's right for you. Want to pair up and make babies and live happily ever after? Go right ahead. Want to pursue two guys/girls at once? Go right ahead, but make sure they're aware of it and ok with it. Want to throw caution to the wind and boink everyone you can? Uh... now you're pushing it. Slow down there, Tiger. There's one good rule everyone should follow when pursuing any sort of romantic/sexual contact: DON'T BE AN IDIOT.