"One who knows the transcendental nature of My appearance and activities does not, upon leaving the body, take his birth again in this material world, but attains My eternal abode, O Arjuna." (BG 4.9)
Krishna, the Supreme Lord from Whom the entire spiritual and material creations emanate, is the emperor and source of rasa which rests dormant within His very Self. He knows rasa is there within Himself; He can feel its presence. Yet He remains unable to taste or relish it. This is because the essence of rasa is reciprocation (spontaneous pastimes).
Reciprocation requires a second personality; a devoted soul who evokes that loving flavor from within; a beloved who draws it out, collects it, shares it, and then dispenses it to others. This can be understood to be similar to an affectionate cow, who requires a milk maid to draw out her milk which then provides sustenance to the entire family.
Thus to experience rasa, Sri Krishna, the One Cause of all causes, expands into Two - the Divine Couple. Krishna needs Radha. It is only within Their heartfelt exchanges in Vraja that the perfection of His love finds reciprocation. This dynamic frees the rasa within Him to flow without restraint. Within Their interactions, Krishna tastes and relishes rasa to His heart's content. Thus through Their spontaneous pastimes, Krishna's purpose and desire is fulfilled.
Yet Radha goes further. Not satisfied with Her good fortune alone, She distributes rasa, which is enhanced with the additional flavor of Her unlimited grace. Srimati Radharani is the emporium of rasa, which extends throughout the land of Vraja as She touches, inspires, and directs the hearts of all Her subjects. Thus Her madhurya rasa dominates within that sacred Abode, covering all the inhabitants with the sweetness of Her madhurya prema (affection of a lover).