Radha Krishna

Lord Krishna did not marry Radha, purposely to prove the world that Love & Marriage are two different realms. Love is a selfless emotion while marriage is an arrangement bound by commitment.. Krishna acknowledged the divine & untainted love of Radha with his divine grace. The pure transcendental love that Radha Krishna enjoy is the highest level of bliss, expressed spontaneously in the form of being paramours, not as a man and wife. 

As the relationship between a man & woman is limited to marriage, Radha Krishna relationship transcends all definitions that are earthly, physical & material. Some limitation is imposed by the sense of 'duty' that husband & wife naturally acquire towards one another. This sense of duty is beautiful, but the Eternal love without any expectation is even more beautiful. It is so profound that it requires no sense of duty as it flows absolute & spontaneous breaking away all barriers of usual limitations. Radha is not a separate individual from Krishna because they were bound by eternal love as a single entity and as two seperate individuals are needed to get married. Krishna and Radha were eternally bonded so strong, That's why we always say Radhe-Krishna and never as Rukmini-Krishna. Rukmini had done a lot of work to acquire Krishna. She had gone against her brother because Rukmani, like Radha, was in love with Krishna. Rukmini sent a letter composed of 7 touching poems to Krishna asking him to take her with him & this touched Krishna's heart as he accepted Rukmini's plea & make her his first wife. The marriage of Radha & Krishna, on the other hand, doesn't really matter because they were bound by eternal love which equates that they had already transended past the marriage level..