Originally Posted by swmnkdinthervr
Wouldn't we as primary partners to some degree be able to limit the depth of both interaction and commitment that we contribute thereby limiting the initial or eventual separation (if that's even the word) between us as the primary couple?
In theory, yes. But that means that if you do feel yourself falling deeply in love with a new partner, you will have to be very conscious about holding back and making boundaries that work for everyone. That is a very good thing to do in the beginning of a new relationship, as unrestrained involvement can lead to you getting swept away and doing foolish things. However, in the long term it may lead to sadness and frustration for both you and the outside partners if the rule is that the newer relationships must always remain "secondary" so as to protect the "primary" relationship.
Many people do poly within that heirarchical model, so it certainly can be done. But I would encourage you to stay open to the idea that bringing in new partners and loving them sincerely can change your lives, and that you may need to, in time, and with rational thought and respect for the original relationship, release some control and let each relationship develop into what it wants to be. If that makes any sense?
It can seem like a scary thought, the idea that a new partner could some day become as important to you as your old partner and that you might want to share your life with them as deeply, but to reject the possibility entirely is to leave yourselves with no choice but to back off or break up with new partners if it does come to that point. Love isn't predictable.