There is also the idea that many monogamous people with no 'hands on experience' of non monogamy view things. I had a friend that was so relieved to meet me, simply because she and her boyfriend had been in an open relationship, and he cheated. All her friends just rolled their eyes, how can you cheat if it's open?? Well, being open, non monogamous, poly, doesn't mean there aren't agreed upon rules or boundaries! It's not a free for all! However, I think that's how a lot of people see it.
OP: Perhaps reading the blogs and other posts here might help you out. A vast majority of people here actually have relationships that have MORE work and boundaries and commitment just because to keep more than one relationship working takes more! You have to balance time, emotion, maturity, and many times finances, among not just you and a spouse (like in a marriage), but between you and him and her and so on. It doesn't mean unprotected sex free for alls or group sex at any opportunity! At least, not for everyone.