IIT Patna: Is it love or lust? I’m confused!

Following is an excerpt from a samvaad (dialogue) session with Acharya Prashant.

Questioner (Q): My question is about relationships. As a boy, I might get attracted towards a girl, but eventually, that girl may become a close friend of mine. How can I know whether the feeling I have for the other is true love or just physical desire, like infatuation?