That was the depth of love that prevailed between the two. That Rama could not hold the innermost recesses of his heart shut tightly any more - as he could remain before his mother and his brother - and that his feelings flowed out so very naturally the moment he saw the one and only asylum for his troubled soul is a quick but indeed a vivid stroke that the expert hand of the Poet has drawn to illustrate the love that Rama had for his
Sita.
Rama then quickly narrates the predicament of his father due to the boons that he had given earlier to Kaikeyi and the change of decision that it had resulted in. "The preparations for my consecration, arranged through the emperor's endeavour, being complete today, the king was pressed hard by her to grant those boons and, having been bound with an oath, was completely brought under her thumb on grounds of morality. I must take up my abode in the forest of Dandaka for fourteen years and furthermore Bharata has been nominated by my father for the office of Prince Regent." (Valmiki Ramayana, Ayodhya Kanda, Canto XXVI, Sloka 22 and 23)
Compare the Sloka with what Rama uttered to Kausalya. The message is the same. But one can see that the emotions that show through his words now, are absent absolutely there. "The emperor is conferring the office of Prince Regent on Bharata and exiling me to the Dandaka forest as an ascetic on the other hand. As such I shall live in a lonely forest for six years and eight, wearing the barks of wild trees and living on fruits and roots." (Ibid, Canto XX, Sloka 30 and 31)
The words sound rather plain. His voice must have been as flat as that of a TV newsreader. The Slokas in question do not say anything about the King or Kaikeyi. 'The king has appointed Bharata as Prince Regent instead. I will spend fourteen years in the forest.' That is what Rama says and the words do not refer either to the situation, or to the qualities of Dasaratha or that of
Kaikeyi.
As against this, read the Sloka by which Sri Rama narrates the decision to Sita. "The king was pressed hard by her to grant those boons,' he says. 'The King had no choice in the matter. He was pressed hard by Kaikeyi. He was kept under her thumb. He had no other go.' The attitude is more conciliatory towards Dasaratha and not so towards Kaikeyi. He expresses what his heart is loaded with at the moment - repeat, at the moment - now. Emotions show through now. The kind of remarks that he did not utter to Kausalya and could not utter to Lakshmana flow out freely now. Kausalya, though his mother, was a queen too as was Kaikeyi and he could not set one against the other. Lakshmana obviously was not in a frame of mind that could have received these words calmly. He would have been set on fire the moment Rama let him know his feelings.
But here, here lies his heart. Here lies the sanctuary of his emotions. Here is the very core of his being. There are no constraints that stop him from speaking his heart out. He is so comfortable with his loved one, and he pours his heart out.
Rama does not stop there. 'I have come to take leave of you,' he tells Sita. I am exiled. You stay here. You look after my mother and father, as you would your own. Take care of Bharata and Satrughna. "As such I have come to see you while on my ay to the lonely forest (of Dandaka). I should never be praised by you in the presence of Bharata (whenever he calls on you in order to pay his respects to you, lest you should forfeit his goodwill)." (Ibid, Sloka, 24)
'Don't speak highly of me in the presence of Bharata. You may tend to speak of my good nature (as you perceive it) in giving up the throne in his favour. Do not do so.'
Elaborate instructions of a loving husband who has a very long term lying before him, to serve in separation indeed!
That was the depth of love that prevailed between the two. That Rama could not hold the innermost recesses of his heart shut tightly any more - as he could remain before his mother and his brother - and that his feelings flowed out so very naturally the moment he saw the one and only asylum for his troubled soul is a quick but indeed a vivid stroke that the expert hand of the Poet has drawn to illustrate the love that Rama had for his
Sita. 
As against this, read the Sloka by which Sri Rama narrates the decision to Sita. "The king was pressed hard by her to grant those boons,' he says. 'The King had no choice in the matter. He was pressed hard by Kaikeyi. He was kept under her thumb. He had no other go.' The attitude is more conciliatory towards Dasaratha and not so towards Kaikeyi. He expresses what his heart is loaded with at the moment - repeat, at the moment - now. Emotions show through now. The kind of remarks that he did not utter to Kausalya and could not utter to Lakshmana flow out freely now. Kausalya, though his mother, was a queen too as was Kaikeyi and he could not set one against the other. Lakshmana obviously was not in a frame of mind that could have received these words calmly. He would have been set on fire the moment Rama let him know his feelings.
Rama does not stop there. 'I have come to take leave of you,' he tells Sita. I am exiled. You stay here. You look after my mother and father, as you would your own. Take care of Bharata and Satrughna. "As such I have come to see you while on my ay to the lonely forest (of Dandaka). I should never be praised by you in the presence of Bharata (whenever he calls on you in order to pay his respects to you, lest you should forfeit his goodwill)." (Ibid, Sloka, 24)
