What is love? What is friendship? What is infatuation? What is the connection/difference between these three?

 What is love? What is friendship? What is infatuation? What is the connection/difference between these three?

Is love simply an infatuation, a biological desire to reproduce? Is it controlled by our biological hormones or is it much more complex? Why is human love different from animal love? Is love what Hollywood, Bollywood, Tollywood, Kollywood, Sandalwood portrays? Is love friendship? How are the two different?

 

 I have heard lot of people started relationship as a friend ends up with love. So I would like to know the difference between these two. Is it acceptable being a friend for certain period and then become a lover afterwards?. Does it not amount to injuring friendship?. At the same time, one cannot love a person with out having friendship. Then, What would be the intention of the person who becomes a lover when he started his relationship as a good friend? Can I say that the person is cunning or wolf in sheep skin?. Because he hid his true motive. Whatever he did was to cheat the other person?. Explain please. I am confused.