“Śrīmatī Rādhikā is the highest shelter of prema, and She Herself has three aspects. One aspect is the root, and the other two are Her expansions. In Vṛndāvana, especially in Govardhana, Nandagaon, Varṣāṇā, Rādhā-kuṇḍa, Śyāma-kuṇḍa, and similar places, She is Vṛṣabhānu-nandinī. She is the root, and She includes Her expansions as well. She never leaves Vṛndāvana. In Nandagaon (Uddhava-kyārī) She is Viyoginī-Rādhā after Kṛṣṇa went to Mathurā. The astonishing madness of separation She experienced as Viyoginī-Rādhā is recorded in Bhramara-gīta.
“As Saṁyogīnī-Rādhā, She spent three months in Kurukṣetra, where She met with Śrī Kṛṣṇa. Although this is the aspect of Rādhikā who meets with Kṛṣṇa at Kurukṣetra, Her desire cannot be fulfilled there; She wants to go back to Vṛndāvana. It is the same Kṛṣṇa there in Kurukṣetra, but in a different dress. There is no flute in His hand and no peacock feather crown; He is not Yaśodā-nandana, Nandanandana, Rādhā-kānta; He is not addressed by those names. The mood there is very different, because there are so many elephants, horses, and a huge army, and Vasudeva and Devakī and all their associates are present. There is no forest like Vṛndāvana there, no Yamunā, no peacocks, and no deer.
“Śrīmatī Rādhikā tells Śrī Kṛṣṇa, ‘My heart is not satisfied. There is not even one drop of the ocean of rasa of Vṛndāvana here in Kurukṣetra. I don’t want to be here.’
“Kṛṣṇa tells Her, ‘You should meditate, and You will realize that You are always with Me. If You meditate, My lotus feet will appear in Your heart.’
“She replies, ‘My heart and mind are the same, and my mind is Vṛndāvana. So You should come to Vṛndāvana.’ This is the meaning of Ratha-yātrā. The ratha-cart is the chariot of Rādhikā’s mind, the chariot of Rādhikā’s desire, taking Śrī Kṛṣṇa back to Vṛndāvana, back to Vraja (represented by the Guṇḍicā temple). Saṁyogīnī means that there is samyoga, a meeting between Rādhā and Kṛṣṇa, but Rādhikā wants to go back to Vṛndāvana. She wants to return to the forest of Vetasī trees; that is, the forest of Kadamba trees, the forest which is fragrant with beli, cāmeli, and juhī flowers. She wants to take Kṛṣṇa there.
“So, first Rādhikā is Vṛṣabhānu-nandinī Rādhikā. Second She is Viyoginī-Rādhikā, who is always in a separation mood and absorbed in citrajalpa, prajalpa, divyonmāda, and other such bhāvas of separation. And in Kurukṣetra She is Saṁyogīnī-Rādhā.
“Saṁyogīnī-Rādhikā is meeting with Kṛṣṇa, but there is no happiness because all the sweet stimuli of Vṛndāvana are missing. Kurukṣetra is filled with many outside elements that are contrary to vraja-prema. Therefore, Rādhikā situates Kṛṣṇa on the chariot of Her mind and, along with all the other gopīs, brings Śrī Kṛṣṇa back to Vṛndāvana. This is the meaning of Ratha-yātrā, and these are the moods Mahāprabhu relished in Jagannātha Purī.”

―Śrīla Bhaktivedānta Nārāyaṇa Mahārāja