Actually the so called true love between a man and a woman (who are not married to each other) is not exactly love but actually it's more of physical attraction between them due to the physical attributes of each other which leads to passion in between them. Because the question is: - How can a man & a woman who do not know much about each other or who haven't done anything significant for each other fall in love with each other? Interestingly people don't fall in love with their parents or siblings to that extent!
If a man & a woman come in contact with each other and start spending time with each other and if they find each other to be physically appealing then they'll start feeling attracted towards each other & would start feeling that they have fallen in love with each other. Such type of love can happen for more than one time in a person's life as opposed to what was told in some old Hindi movies that love can happen only once in a life time. A man can like or fall in love with more than one female in a life time and vice versa. In some cases the love in not bidirectional as man can get attracted towards some woman but the woman is not feeling attracted towards that man and vice versa.
As opposed to earlier times, these days, when females are going out to study & to work in organizations or are becoming self employed, chances of male-female interactions have increased. Due to the advancement in communication technology scope of networking has become easier which has also leaded to more male-female interactions. Many males and females are coming close to each other via social networking sites like Facebook.
According to Dr.A.S.Kalra there can be only one definition of true love & that is: - Ability to help each other not only in good times but much more in the times of adversity because it has been observed in many cases that after marriage many people tend to leave their spouse if the spouse falls ill for a long interval of time. Similarly it has been observed in many cases that many wives left their husbands, who were financially very rich earlier (before their marriage) because sometime after marriage husband observed severe financial crisis for some interval of time and now he could not spend money on buying luxuries to his wife.