"Why Radha and Krishna's marriage never took place...?"
The love between Krishna and Radha is eternal. Krishna did not marry Radha to show an example to all the lovers of this material world. Even though Krishna loves Radha eternally in his heart, soul, body and mind, he did not marry her. Krishna had a mission, lesson to deliver to the world -The essence of Bhagavad Gita. So, he left his love, Mathura for us. He taught us how to detach ourselves from attachment to pursuit the supreme goal of life (spiritual advancement).
He taught us how to sacrifice love for the sake of others. We obviously see nowadays that lovers - teenagers, adults are separated due to various circumstances, marry someone else without forgetting the one who stays in their hearts. Likewise Krishna did not forget Radha even though he married Rukmani, Satyabhama.
True lovers definetely get united one day in this life or the next life. Krishna and Radha statue erected in temples show us to believe in love and accept their unique love story.
Another view:
Krishna could not marry Radha because she was related to his father and was in a way his aunty. Very few people know this truth.
One more view:
Krishna is soul and Radha is mind. Soul (Krishna) controls the mind (Radha) and after enlightenment they become one. In marriage man and woman would have separate identity and therefore after enlightenment only soul control every action so no new Karma bondage.
[content link wikkianswers]
[photo courtesy Google]
