Oh, making it polyamory wouldn't have made anything less complicated or easier, quite the reverse! But at least it would have been more interesting than a bog-standard love triangle/quadrangle. And a poly relationship doesn't mean that everyone involved has sex with and loves everyone else in the relationship; being in love is not a transitive property. What it does mean is that it turns things from betrayal to working together. Dee and Sam don't need to be in love, but I do think they would be good friends and it would have made things much easier for both of them if they could have worked together to manage Lee and Kara, both of whom are very high-maintenance.