I can understand your perspective, but I want to offer an alternative view, maybe less bound to societal preconceptions. I married my partner for many reasons, financial, wanting to raise a child together, wanting to share my life with them… But staying married for the rest of our lives is a crazy concept for us. The marriage has its purposes, but we both know that life can change and that we could decide that we had a good time, and that now the time has come to move on. A marriage is less romanticised for us, it has practical reasons. I guess being polyamorous helps with defining new relationship ideas on many levels ;)