If Mahaprabhu is in Puri, but in Navadvipa Mother Saci is crying while making an offering to Him, would she be satisfied if He were to appear there in a mere kaya-vyuha expansion? Knowing that she would only be satisfied if He came in His original form, He does just that, and it is the same with Srimati Radhika. In His original form Krsna always remains by the side of Radhika, and is never able to be separated from Her.
Srila Sanatana Gosvami says that because the vraja-devis possess the paramount mahabhava-yavadasraya-vrtti, how could Krsna ever leave them? Even while residing in a foreign land He visits them in Vrndavana in His original form, and only them, not others such as the sakhas.
rakhite tomara jivana, sevi ami narayana,
tanra saktye asi niti-niti
toma-sane krida kari’, niti yai yadu-puri,
taha tumi manaha mora sphurti
mora bhagya mo-vasaye, tomara ye prema haye,
sei prema-parama prabala
lukana ama ane, sa ga karaya toma-sane,
prakateha anibe satvara
Cait.-carit. Madhya-lila 13.154,155
Sitting alone with Radha in Vraja, Krsna says, “My dearest Srimati Radhika, in the distant land of Dvaraka I have married many ladies, but in reality I don’t love any of them as I love You. I searched the entire universe for one kisori whose beauty, complexion, and nature was like Yours. I found Satyabhama, but I remain with her only because she reminds Me of You; and similarly I have married sixteen thousand queens because each of them reminds Me of the gopis. If somehow that remembrance of You were to be lost, I would leave them all at once. You say that when We are apart You feel as if You are dying, but I am constantly meditating on how to save Your life, and for this purpose I worship Narayana. By His mercy and mystical potency, I am able to come to Vrndavana every day to enjoy Your company. You consider My appearance to be in Your meditation or in a kaya-vyuha form but I come to Vrndavana in My original form. My great good fortune is the immense love that You have for Me. Unknown to everyone in Dvaraka and in Vrndavana, I come here to You, and hopefully very soon I will also be visible to everyone else here.”
SOURCE : Bhakti Rasayana page 102 - 103