Why we fall in Love?

Falling in love is not a new thing in this world. There are number of people from around the world who fall in love with someone. Love is one of the commonest and most felt emotions around us. However, still no one knows the answer of this question. Some people may have tried to find the answer for this question but mostly very few are able to get success. The main reason behind this is various factors which also vary for person to person. Therefore it becomes very difficult to find a single answer and conform it as the main reason. Only we can do is to find different suitable answers and group them to find a single suitable answer.