Divorce doesn't have to be this way. Monogamy doesn't have to be for life. Some people just tend to focus on having one partner at a time. Since the stigma of divorce is lessened, people are having amicable divorces more often. Instead of looking at the years of marriage as a wasted of time, people are able to look back on those years fondly.

If you think monogamy all about jealousy, then I can totally see why you think it's selfish. Monogamy is about love. Love is a deep affection for someone. Love is a commitment to your partner that is beyond sexual gratification. Monogamous love is about selflessness. The best monogamous relationships are when you consider your partner's needs before your own (and visa versa). I don't know what polyamorous love is about, because I'm not polyamorous. I'll do me, you do you.