I believe that people love for a number of reasons. One reason why people love is because we are taught by society that there is someone out there that is perfect for everyone, and if we want to find them, we have to love in order to do so. Another reason why people love is because humans are social creatures, and loving is a part of our social skills that are innate to us. Lastly people love in order to receive love in return. To be loved is a warm, comforting feeling, and in order to receive it to others, we have to give some ourselves.
I believe that the main reason why people continue to allow themselves to fall in love is because of the high regard that society puts on it. In the days where most marriages were fixed and young adults had no control over who they married, "falling in love" was not an option and, therefore, did not hinder them. Also, human beings are social and interacting with others in a way to show love is a part of who we are. Finally, people love because they like to receive love back. If love was a feeling that others did not enjoy, they would not readily inflict that feeling on people that they care about. For this reason, I believe that love is a positive feeling that people give off because they expect to get it in return.
There are many factors that contribute to the reasons why people choose to love --- society, human nature, and the reciprocation that love entails. All of these factors contribute to the reasons why people fall in love and work together to keep the bond between two people as strong as it is.