While my parents were not successful with poly long term, they were adherents. I was brought up to believe it was completely acceptable to love more than one. My first long term relationship was a polyfi vee, and I adored my co-wife. It ended when our hinge died - but she and I are still close.
I would say my only downfall to security is finding others who are like-minded. I find that I don't understand jealousy and am often confused by those who feel it.