I'm not sure how it happens, maybe through a combination of TV, movies, books. You know, through fictional accounts from a number of single creative minds, usually struggling with loneliness and resolving it with a fantasy about love, we are given the impression that love is a state of euphoria that one reaches. Marriage is the way to guarantee the euphoria will never end. These are the cultural myths perpetuated by religious organizations and Hollywood money-makers. Then reality sets in. There are money problems; kid problems; perception problems.
Two parents working is not enough to make ends meet; or, if it is enough, both parents are completely exhausted and have virtually no time to hug each other.
Kids learn new words like "moron" from their playmates at school, and they throw around the such words loosely, alienate relatives, and we defend them because we love them. Kids can't remember what they learned in school from the last year, yet our taxes are high because the schools are so good.
One spouse perceives Obama as peacemaker, and the other cannot see one constructive action Obama has done to establish peace. One spouse thinks national health insurance will save money; the other thinks it will bankrupt an already bankrupt nation.
Half of marriages end in divorce. The other half do not because the individuals involved probably have a realistic expectation of what love is -- it is caring enough to be flexible, to say you're sorry every 15 minutes (as John Lennon contended), and to understand that sexual attraction wanes.
Love is a many splendored thing, and most of all it is a renewing commitment to working together to meet the problems, one day at a time, one problem at a time. That's real love.