Why are you anti-polyamory??

Me
I was browsing the comments on today's sex quiz about polyamory and was shocked by all the condescending comments you ladies left. My question is, putting your jealousy and possessiveness (societal norms as well) aside, why are you so against it? Most women I know, including me, have been cheated on/lied to by their mates. So basically, in my mind, you were in an open relationship minus the openness and honesty. How is that any different? You're in the dark about their other partners (and being treated as an option), all the while you're treating your partner like a priority and sitting home alone while they're having a ball. Anywho... I was just wondering where all of the animus was coming from.