Originally Posted by apophis
This is for the simple reason that the choice to be monogamous is most often based on the choice to be in a partnership where you use your available resources (time, energy, attention, etc) mostly with one person.
Monogamous partners are those who decide that they individually want to give most of those resources to one person and want to receive the same amount in return.
I find your definition of monogamy interesting and a bit misguided because that is not what most monogamous relationships, in my experience, are. In my experience, people do not decide individually that they want to give most of their resources to one person, nor do they discuss what monogamy means to them. Most people enter relationships with the cultural background of monogamy. They learn their role from how their parents, friends, and other family members do relationships. They assume that their partner understand what they mean when they want to form a relationship. When I met Runic Wolf, he was my night in shining armor, literally because he stood up to my abusive step father and wouldn't take anyone abusing me. I fell in lust and then love with him. I knew that I didn't want to lose him, ever and he didn't want to lose me either. Which meant that we should get married, because that was the logical conclusion to draw. . . if you love someone and you want to spend the rest of your life with them, you get married? Right? But did we talk about wanting to be devote almost all of our time to each other? No. We talked about having kids some day, sharing finances, our values, religion, gaming, and how much it sucked to not see each other when he was in basic training. We never said it would be exclusive, but we never said it wouldn't either, at least not before we got married. And to be honest, the large majority of the population doesn't talk about it either. They either don't know that their are other options or assume that their partner knows and shares their views.