I had a pretty interesting discussion with one of my friends over lunch today about the nature of love and the meaning of marriage. I'll try to distill it down into a few paragraphs, but as the conversation was a couple of hours long that may not be easy.
The main difference in perspective can be explained thusly: for her, loving someone is the same as being "in love" with someone; for me, being "in love" is a mere emotion, and actually loving someone is a decision to act in a certain way. Emotions are fickle (at least mine are) -- they come and go seemingly at random, and are hardly under our control, if they are at all. Emotions are governed largely by chemistry; it's difficult for our will to subjugate our emotions. A great many people don't even see any value in controlling their emotions, and our culture encourages us to pursue happiness on these grounds.
If it feels good, do it. Listen to your heart. How do you feel? This is how most people seem to view love, and I think that this view is intertwined with our cultural construct of dating and has a heavy influence on marriage. People look for someone who makes them feel all warm and fuzzy inside. I call this "emotional lust". The essence of lust is the desire to use someone else to fulfill your cravings, and although it usually refers to physical desires I think it's equally applicable to emotional needs as well. It's generally acknowledged that men make many decisions based on physical lust, but it's not widely recognized that women tend to make many decisions based on emotional lust. As I said, our culture actively encourages this perspective.
Therefore, when a couple is "in love" and emotionally involved and intimate, they decide to get married based on those emotions. They ride high for a while, but eventually those emotions come to an end. It's basically inevitable. People are highly adaptive creatures, and eventually the spouse becomes a part of the environment and the highly charged emotional energy that was there at first dissipates. Clearly, marriages that are based purely on physical lust cannot be expected last, but for some reason people expect emotional lust to be different. The median American marriage lasts 7 years.
What, then, is the alternative? Approach love as a decision, rather than merely as an emotion. There is nothing wrong with the emotional aspects of being in love, but it's important that there be more to a relationship than just those emotions -- repeat after me: emotions are fickle and they don't last forever. Once the emotions are gone, many people find themselves stuck with a person they aren't even friends with. Since those emotions were the foundation of the relationship, it's over.
However, when you decide to love someone, and you make a committment to stick by them, work together, and share each others' lives regardless of circumstance, then the relationship is built on a more certain foundation. When emotional lust does not control, then the focus of love can be on the other's well-being rather than on merely satisfying your own cravings.
Many people view dating as a means of fulfilling their emotional lust. Being with anyone is better than being with no one, because at least you aren't alone. The most important thing about any person you date, then, is how they make you feel. Only when the feelings begin to drain do other components come to the fore: is there a spiritual and intellectual connection? Do the math: many friendships last a lifetime, but very few marriages do. Why is that? You may think it's because marriages are a lot more demanding than most friendships, and that is exactly right. There is no way that any human being can live up to our expectations and desires, and if you try to lay all that on your spouse you are bound to be disappointed.
Finding a spouse should be like finding a best friend, and indeed I believe that ideally friendship should come before love. It's hard (ok, impossible) to avoid falling "in love" with people sometimes, but it's important not to let those feelings take over a budding friendship. It's very easy to fall in love, but it can be very difficult to get out later. Being "in love" is a wonderful feeling, but it won't last and it's no basis for a permanent relationship.