I shall gather some evidence re the inexplicable and trancendental oneness and difference between Srimati Radharani and Satyabhama in Dwarka
This is Prabhupada teachings of Lord Caitanya quote below..and I have the book ” Mathura meets Vrndavana”  by Srila Gour Govinda Swami, I will refresh myself of his teachings of prema vivarta ..trancendental union in separation…

My feeling is

Radharani knew Krishna could not exist without Her and vice verser …so in Dwarka Radharani expansion as Satyabhama arrives to satisfy somewhat Their separation from each other ..
So these arrangements came about , a  trancendental lila ..
..the simultaneously and inconceivably oness and difference tattva, I think we will see  permeate this tattva…

An over emphasis on the oness or the difference would be incorrect tattva.

Srila Prabhupada

“In Govinda-līlāmṛta there is a verse that states: “Who is the breeding ground for Kṛṣṇa’s affection? The answer is that it is only Śrīmatī Rādhikā. Who is Kṛṣṇa’s most lovable object? The answer is that it is only Śrīmatī Rādhikā and no one else.” Sheen in the hair, moisture in the eyes and firmness in the breasts are all qualities present in Śrīmatī Rādhikā. Only Śrīmatī Rādhikā is able to fulfil all the desires of Kṛṣṇa. No one else can do so.

Satyabhāmā is another competitor of Śrīmatī Rādhārāṇī, but she always desires to come to the standard of Śrīmatī Rādhārāṇī. Rādhārāṇī is so expert in all affairs that all the damsels of Vraja come to learn arts from Her. She is so extraordinarily beautiful that even the goddess of fortune and Pārvatī, the wife of Lord Śiva, desire elevation to Her standard of beauty. Arundhatī, who is known as the most chaste lady in the universe, desires to learn the standard of chastity from Śrīmatī Rādhārāṇī. Since even Lord Kṛṣṇa can not estimate Rādhārāṇī’s highly transcendental qualities, it is not possible for an ordinary man to estimate them.”

Thus, Krishna sits on His rooftop house in Dwarka thinking about the residents of Vraj and Radharani and the gopies with tears flowing down his cheeks and calls for Uddhava to deliver His messages of love .

And at Kurukshetra Srimati Radharani says , That very personality who stole away my heart during my youth is now again my master. These are the same moonlit nights of the month of Caitra. The same fragrance of malati flowers is there, and the same sweet breezes are blowing from the kadamba  forest. I am also the same lover, yet still my mind is not happy here. I am eager to go back to that place on the bank of the Reva under the Vetasi tree. That is my desire.”

More on this later ..

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