Love means two persons, there is exchange. Giving something, taking something, feeding something and to eat something, and speaking everything, no secrecy, and to know everything of the other person. When these things are transacted, then there is love. Dadati pratigrhnati bhunkte bhojayate caiva guhyam akhyati prcchati. If I love you and I have got some secrecy, I don't disclose to you, that is not perfect love. I must deal with you open-hearted, you must deal with me open-hearted, then there is love. This is one of the basic principles.
Srila Prabhupada – Evening Darshan, Tehran, 9th August 1976