Jon,
Do you believe that humans are capable of complete sexual monogamy? Yes.
Does gender figure into the equation? Sometimes.
Are women or men least likely to remain sexually faithful to their partner, and why? Men. Hormones.
Does sexual orientation figure into the equation? If men are more likely not to remain monogamous, is it that much harder for two gay men to maintain a sexually monogomous relationship? It varies (I guess)
As I've stated above I do believe in the concept of emotional monogamy, ie being in and staying in love with the same person for life. Interesting hypothesis. Many things are humanly possible. It's possible to live on chef salad, but who'd want to? I'd think a better question would be: is it likely for the average person?
I posed this question to a group of people in my book club and received responses that varied greatly. One woman in the group agreed with my view that sexual monogamy was not a realistic goal, while one of the men in the group basically told me I was full of shit. I'm not looking for moral judgements but for your thoughts on the concept.
It does not surprise me that you would get varied answers to your questions since people are different. Even when the same person answers, life situations change, different viewpoints develop while others become obsolete. There are no absolute, one-size-fits-all answers to questions like this.
tj