Your views are similar to mine on the topic. Occasional sessions but keeping your family as a priority is not like sneaking off to be romantic and holding their hand in hand in the park. As far as when it became normal for humans to be monogamous, that is curious. It does come natural to most people. I'm very much monogamous. With my late husband, as long as I knew and approved of the dom he was seeing, usually picking her out myself and taking care of the pre-session conversation, it didn't feel like cheating at all. It was actually fun to send a sealed letter with him to the dom and his knowing that she and I conspired on what his session would consist of.
