Married again. And again. And again?

I have lived a sheltered, conventional, traditional life. I have not experienced things that almost everyone has these days. One such thing, that I cannot begin to comprehend what it must be like, is to be married more than once. No judgment intended, just genuine puzzlement about how one deals with it. How can you avoid memories, comparisons, good and bad ... all kinds of baggage?Especially if there have been more than two or three or four or more attempts. What must such marriages demand.?Seems as if it would require the emotional maturity of a saint to pull it off. I think of two couples I know pretty well. In both cases they have five or maybe it's six marriages between them. In one case it's his fourth or fifth and her second. For the other couple it's her first and his fourth or fifth. One of these unions is currently at ten years, the other is close to 20. They seem to have finally got it right and love each other a lot. I enjoy watching them together. This amazes me. I wish I could ask them how they do it. Actually, they would probably be glad to tell me.