Why do we fall in love?

Everyone does it at one time or another, but why? We're talking about falling in love. Professor Arthur Aron from State University of New York at Storybrook has been exploring the dynamics of what exactly happens when two people are falling in love.
He claims that our primary motivation as human beings is to expand the self and to increase our abilities and our effectiveness. One of the ways we accomplish this is through our relationships with other people. He says, 'We have learned in our research that it is important to feel that you have the ability to be an effective person, especially in relationships.'
But how does this theory of self-expansion explain the process of falling in love? Usually we fall in love with a person who we not only find attractive and appropriate for us but is also someone who demonstrates that they are attracted to us. According to Professor Aron, this creates a situation with great scope for self-expansion. The fact that they are attracted to us offers a significant opportunity - when we perceive this, we feel a surge of exhilaration!
However, his studies show that it doesn't always work this way. An interesting exception to this occurs if we feel badly about ourselves. The process gets thrown off if we can't believe another person is interested in us-like the Groucho Marx joke where we don't want to belong to a club that would have us for a member. We tend to miss out on opportunities for falling in love if we don't feel good about ourselves.
Professor Aron has also managed to define the conditions which are best for meeting someone and falling in love. He claims that when you meet someone under conditions that are highly arousing-a political demonstration, turbulence on a plane, a stimulating performance-a time when the body stirred up and excited, we tend to experience attraction at a heightened level. This effect is well documented, but the explanations for it are very controversial. Professor Aron believes that we come to associate the arousal of the situation with this person and our own self-expansion.

It's also interesting to look at when people fall in love. How long do you have to have known someone before you realise you are in love with them?
'Contrary to what most people think, the statistics show that most people fall in love with  someone that they have known for a while. People only report falling in love quickly about 30-40% of the time.' says Professor Aron. he also points out that this varies from culture to culture-falling in love happens differently between cultures, but it does occur in most cultures.
I think the most of us think that our appearance must factor into the equation of falling in love. Professor Aron says,'This is interesting. We have found that if your unattractive, it can hurt you a lot in forming romantic relationships. However, being attractive doesn't help that much.' The professor has found that two important characteristics, kindness and intelligence, are vital to the process of falling in love. And attractiveness is not connected to these things. These two attributes are things that people learn about someone from knowing them over time. Intelligence is critical in all aspects of life, especially in love. But kindness is the strongest indicator for a successful long-term relationship.
Other research confirms what we all know-that love can make you mad or sad. Some people suffer from a form of Obsessive Compulsive Disorder when they are in love, which means that they are, for example, constantly checking things. At the same time, this disorder can also make you depressed as it affects serotonin levels in the brain. Levels can drop so low that they trigger anxiety and depression. But it doesn't last for ever-after a year levels usually return to normal. It may be that we need this chemical response for relationships to survive as some have suggested that you have to be mad to fall in love!