I recently came across these three ideas in a terrific little book entitled 'Monogamy' by Adam Phillips, published by Faber ...

1.
Profoundly committed to the better life, the promiscuous, like the monogamous, are idealists. Both are deranged by hope, in awe of reassurance, impressed by their pleasures. We should not be too quick to set them against each other. At their best, they are both the enemies of cynicism. It is the cynical who are dispiriting because they are always getting their disappointment in first. (p. 3)

2.
At the beginning of a love affair one might ask - depending on which kind of person one is: a person who prefers the future, or a person who prefers the past - What am I getting into? or, What am I getting out of? It is common sense to assume that every entrance is also an exit.

The compulsive monogamist never needs to ask these questions. This is what his compulsion is for, to convince him that the future is the same as the past. Outwitting time and change he builds a monument of continuity among the promiscuous ruins. Valuing a relationship because it lasts, he lives as if time proves something. (p. 18)

3.
Babies tell us nothing about infancy because they can't speak. And our beginning, of course, like all beginnings, tells us nothing inevitable or predictable about our middle or our end. Monogamy as our beginning, and our end, is too wishfully neat, too symmetrical for the proper mess that a life is.

But if monogamy is where we start from, our first knowledge is of infidelity; that is what knowledge is about. Temporarily, the mother can be everything to the child, but the child cannot possibly be everything for the mother. He can't feed her or sexually satisfy her, or have adult conversations with her. From the child's dawning point of view the mother is - as the father will soon be - a model of promiscuity. She has a thousand things to do. She knows other people.

Small children, like uxorious husbands, are the most devoted of partners to their parents (they like coming with them to the toilet). Their parents, however, libertine if only in their responsibilities, have other commitments. Small children understand monogamy. Adults often find it daunting, even beyond them. (p. 75)

Adam Phillips was the Principal Child Psychotherapist at Charing Cross Hospital, London.
He's written several books.
Cheers,
Mike.