Srila Bhaktisiddhanta Sarasvati Thakur Prabhupada writes in the Harmonist that:
“Srimati Radhika is the guru of the inner circle of the servants of Krishna. Srimati Radharani however accepts the offering of service of only those souls who are especially favored by Nityananda and are deemed by Him to be fit for Her service. There is therefore a most intimate relationship between the function of Nityananda and that of Srimati Radharani.”
It is also important to note that Nitai’s complexion in Kaliyuga is bright molten gold, rakta gaura kalevarah, just like His brother Gaurhari who has come to distribute Radha prem. Gauranga has accepted two things, radha bhava kanti dui angikara kari’, Radha’s bhava (mood) and Radha’s kanti (complexion). In the same way, Nitaichand who is completely enveloped in Gaur bhava and constantly sporting in Gaura prema rasarnava, the ocean of loving mellows of Gauranga, has accepted the complexion of Gaurhari. What is Gaur bhava? It is Radharani’s bhava. Nitai has fully imbibed Gauranga’s mood and is distributing to the whole world this unnattojvala rasam, Radha prem. This can be seen in the childhood Ekachakra pastimes of Nitai when He exhibits the deep mood of separation of the gopis for Krishna, which is incomprehensible even for the paramhansas situated in other rasas.
apani ye gopibhave karena krandana
nadi vahe hena, saba dekhe sisugana
(CB Adi 9.36)
Accepting the part of the Vraja gopis, Nityananda wept bitterly in a mood of intense separation. His tears flowed like a gushing river and all the boys looked on in amazement.
Note: Nitai is Himself displaying gopi bhava, which proves that He is fully cognizant of the bhavas of the gopis situated in madhurya rasa.
This is the first hidden and confidential reason for Nitai assuming this golden form. The second reason is that Nitai has also simultaneously accepted the mood and complexion of His own antaranga shakti, Sri Ananga Manjari.
Thus, one can attain Gaur bhava and Radha bhava only and only if they take full exclusive shelter of Nitaichandra.
If we also speak in terms of the nitya lila, then there is one very important aspect of the lila without which no pastimes can take place. When Radharani was approached by Krishna to come to the material world and assist Him in His pastimes, Radharani laid two conditions. The first and foremost condition was that Vrindavan dham must be there. The conjugal pastimes of Sri Sri Radha Govinda must take place ONLY in Vraja dham. Even when Krishna appeared before Radharani in Kurukshetra a hundred years after leaving Vrindavan, Radharani was not pleased in that atmosphere. Instead She begged the Lord to go back to Vrindavan and continue His loving pastimes there with all the Vraja vasis.
tathāpi āmāra mana hare vṛndāvana vṛndāvane udaya karāo āpana-caraṇa
“Although We are both the same, My mind is still attracted to Vṛndāvana-dhāma. I wish that You will please again appear with Your lotus feet in Vṛndāvana.”
This is the very prayer of Radharani to Krishna, which was recited by Mahaprabhu during the Ratha Yatra in Puri and whose confidential meaning only Rupa Goswami could understand.
Therefore the most crucial component of Radha Krishna’s lilas is the dham. Who is the dham? It is directly Nityananda Balaram. Nitai is the sandhini shakti of Krishna, the holy abode. So without Nitai’s assistance, Radha Krishna’s amorous pastimes cannot be manifested.
It also cannot be forgotten that both Nitai and Radharani are the two internal potencies of Krishna. Just as the Energy and the Energetic cannot be separated, the Energies which are emanating from the Energetic cannot be completely independent of the other either. Both energies are always functioning in accordance to one another. Hence, there is always a link between the function of Nityananda Balaram and that of Srimati Radhika.
Therefore the arguments that Nitai has no connection with Radharani and thus cannot grant one madhurya rasa are completely baseless. Nitai’s connection with Radha is very deep and on a very high platform, which ordinary souls cannot have the capability to understand.