Thoughts on the institution of marriage

While i was packing today, I came across a piece of writing I did in religious studies class when I was 17 about marriage. At that point in time I was very cynical about marriage, & supposed happy ever afters. I ended my essay by talking about a physics class on 'wave theory' where 2 waves will either cancel each other out (peak+trough), or be really low (troughx2) or double in size (peakx2). So my idea was that, surely, there must be people who would complement each other to such an extent that they really would create synergy when they were together (like the peakx2). And yet all the couples around me seemed alot more like the peak+trough. Whether one was dominant and one submissive or they just manipulated each other & tried to control one another, it has been quite discouraging watching a number of friends and family members get married then get separated then get divorced instead of staying together like couples ideally should do. I mean, what is it that happens between falling in love and getting a divorce? Is it selfishness? or ego? or the adversary? or jealousy? or any number of other negative emotions? I have never been married, so I'm only seeing this from an outsiders perspective and perhaps my perception is flawed. Its hard to write about things I know nothing about. Maybe i should stop now. I just want to find an example of a really good marriage where they actually are happy together. One that comes to mind is the late President Hinckley and his wife. They were so lovely together even after all that time. The other is 2 members of my family. They were teenage sweethearts. She passed away earlier this year of cancer & he followed a few weeks later from a stroke. Its been sad for their kids, but i guess he really couldn't bear being separated from her.