Do Opposites Attract?

Regarding the romantic relationships between men and women, the old saying was that "opposites attract."  But current online dating sites or services, especially eHarmony,  seem to focus on similarities between a man and a woman. So which is better for choosing a lifetime mate?
  I think that when you are looking for a friend, you tend to be drawn to a person similar to yourself but when looking for a person to marry, you tend to be most attracted to your opposite. In my experience I have noticed that most people marry a person different than themselves. For instance: day people tend to marry night people; people who are always hot seem to marry someone who is always cold; extroverts tend to marry introverts; the loud, outgoing person tends to marry a quieter, more easygoing person. Think about your own marriage, those in your family and couples you know or have met during your life. Don't you find that to be true?
  So if similarities help to insure compatibility in marriage, why do people tend to choose those with opposite characteristics? Doesn't that almost insure a stormy relationship? I think one of the answers may be that being married to someone with opposite personalities forces us to grow as a person.
  We are all born selfish and self-centered. If we are disciplined and nurtured properly as children, we learn to come out of ourselves and think about others. I think marrying our opposite helps us to continue that journey into adulthood. We learn to compromise since we have to make mutual decisions. We all begin by thinking our way is the "right", the best or only way. Marriage to our opposite helps us to appreciate the God-given differences in people; that individual differences all make up the whole; that God made people different, with different gifts and talents, to accomplish different tasks. One is not right or wrong, just different.
  To conclude, I think that this is one reason divorce is so pervasive in Western society. Many of us have stopped growing and maturing. We are still stuck in the self-centered stage of childhood. We are attracted to and fall in love with our opposite and then shortly afterward (when the glow of being newlyweds wears off) begin to try to get our spouse to be like us!
  The answer is to learn to truly love your opposite. To appreciate their gifts and talents. To learn from them; to give, to change, to compromise. To bear with their faults as you would like them to bear with yours. To think of them, their needs and desires as well as your own. To desire their happiness. That's the secret to a happy marriage.