And I think this is one reason that so many throw away a pretty darn good relationship for another (serial monogamy), because as time progresses those flaws become apparent and the intoxication of first attraction and lust wears-off. People meet someone else that makes them intoxicated with first attraction and lust and perceive them as being less flawed than their current partner. So they move-on only to eventually have the cycle repeat itself.

Being poly allows us to accept our partner’s shortcomings because those areas can be fulfilled by someone else without threat to the other relationship. Like you say, it’s not requiring that everyone be everything to you.