Are harmonious relationships bound to last longer?

In your experience, did fighting make a relationship “bad” or did an absence of conflicts make it “good”? Does some conflict from time to time simply show passion and different opinions or does it have to mean that the partners are intolerant with each other? Where are your boundaries, would you say that a relationship can be nurturing and loving but also contain discrepancies? And have you ever ended a relationship because there was simply too much fighting involved?