Having a significant other has changed over the years. High school sweethearts rarely become husbands or wives. Marriage is less and less common.
It seems like a close relationship is something that is feared, but really isn't so bad. Everyone's afraid of how they'll be percieved by the other, weird habits, smells and so on. But relationships do advance to the point to where it's okay to fart in the other's company.
Then again, another reason why people fear a close relationship is (*gasp*) it might lead to marriage. It's one thing to commit to a job, a job you can quit, but marriage is something that nobody can just quit. Of course it shouldn't be this way, since when marriage happens, the two become one being. Think Yin and Yang, two opposing forces complementing each other.
People are compelled by society to marry, since having children is considered a great service to it. Continuing the species is important, no question about that. The unfortunate part is that so much of marriage has become commercialized that it's seen as just another reason to spend an enormous amount of money for the sake of the relationship (which is done already on Valentine's Day).
Religion isn't helping either, by insisting that people urgently have to marry. They never talk about how important love is in the relationship, they just seem to care about getting people married (probably because it's a chance to get people in church for once), while vigorously opposing efforts by gays who really DO love each other to get married (does nobody see the cognitive dissonance?)
But who needs marriage? Who needs a close, personal relationship? Some people do, and more power to them, but maybe it's time to honor those other people in life that are often forgottten at the expense of the significant other: friends.
People are relaxed about friends. There's no pressure to be good, it's just natural. Friendships aren't challenging at all, they're just natural. Of course, out of this, a marriage could come, but some people are content to just go along for the ride and enjoy their friends. The problem with a significant other is that they are more important than every other friend, and should some friends be more important than others?
A friend in India said once that the problem with having a girlfriend is that "you forget about your friends, and only pay attention to her."
Which he followed with a toast: "No girlfriends, no boyfriends, just friends!"