You must be aware that most men (and also not only a few women) are by nature not monogamous. This nature makes itself even more forceful when tradition and circumstance stand in an individual's way.
... the fact is it didn't happen in the first month, the first six weeks, in a way that was at all acceptable. And since I'm in charge, obviously, we screwed it up.
It's very dangerous to mix up the words natural and habitual. We have been trained to be quite habitual at communicating in ways that are quite unnatural.
Only those young people can be accepted as healthy who refuse to be reconciled with the old order and foolishly or wisely struggle against it - such is the will of nature...