When one is single, one must overcome one's own intellectual and moral and spiritual isolation to branch toward the ultimate compassion: to see the world of another as "the" world for them, and thus to accept it and to wish for its success comingled with one's own (to whatever varying degree the relationship or coupling or moment dictates).
What is scary about relationships is that they create a new world, an "our world." You can see it in older couples who recreationally shop or engage in public activity on the weekends; the world is defined for them, and they seek something external confirming it, but basically its ways and their ways are defined by the relationship itself. You can see it in teenage lovers who - may it work for them, as the first love is the least cluttered - exist in a world by themselves and have no desire to relate to anything else. Finally, you can see it in embittered 27-35 year olds who having formed a relationship nervously consult it as a basis to a lifestyle; in their case (the most pathetic) the concept of relationship in age of life is more important than the tangible relationship itself, as most of them have settled into a 2nd marriage and/or 11th lover, therefore are both bored and afraid of the concept of relationship, thus seek to make a non-threatening one through legalistic contract. The worst are the "empowered" ones, where the contract is almost put into legal terms. There is no actual contact with the process of world-making, and all of the fear and adventure required.
Let me clarify: I'm all for love, and where needed, marriage. Marriage is the commitment to make a lifetime of a love, as one will most probably be creating new life forms merged of the parents. Love is what happens when one finds someone else one respects enough to wish literally union in the form of one's irreplaceable time and possibly spawn. If you look at the process of breeding, it's quite romantic: We work, so let Another be made of Us. My warmth and heartspirit goes out to you teenage lovers; may your idealism never die. It goes out to the older couples who've lived through everything and made it work, should they still have tenderness for each other. And most of all, it goes out to my generation, you intrepid 27-35s, who think you know what you should have and are trying to copy the image from TV screen to life.
But one must acknowledge love's instabilities. First, the choices involved depend on the people involved and more importantly, their knowledge and experience (one doesn't need many lovers for life experience: one needs life experience). You are every experience you've had, and every lover you've had. Over time, the process can become rote and you can cease to be able to tell the difference between lovers. Also, the concept of love depends on what one sees. Your beloved may be hiding a murder, or a betrayal; it's hard to think of ultimate union with something diseased. Finally, love itself may become a prison, when one tries too hard for love and not enough for the literal situation of two people coming together (no pun intended). When I see love held up as a signum imperium in this way, I shudder and think of Christianity.