Well matched couples are praised as being like Rama and Sita. So exemplary was the attachment and regard that Rama and Sita had for each other. Sita held the same values as Her Consort. Yet, there was an occasion when She lied. How then can She be considered a perfect match for Rama, who never spoke an untruth, one might ask. But there was a precedent Sita was following when She lied, explained M.V. Anantapadmanabhachariar, in a discourse.
Hanuman met Sita in the place of Her incarceration, and reassured Her that She had nothing to fear and that Rama would soon come to Her rescue. But Hanuman did not stop with this. He began to destroy the trees in the place, and the alarmed demon women who stood guard over Sita wondered what Sita knew of the monkey. They asked Her who the monkey was. Surely She must know, for She had been conversing with this monkey, had She not? But Sita chose to remain tight lipped about who Hanuman was, and answered that She did not know who the monkey was. This was a lie, for She knew who Hanuman was. Even if Her lie might have been uttered to keep harm from befalling Hanuman, yet the fact was the She had lied.
However, even in uttering a lie, She was only following the example set by Her husband. When Dasaratha banished Rama to the forest, Sumantra drove the chariot to take Rama, Sita and Lakshmana to the forest. But Dasaratha could not bear to be separated from Rama and he called out to Sumantra to stop. Sumantra was duty bound to obey his king. So he hesitated. But Rama told him not to stop, but to drive on. If Dasaratha later questioned him as to why he did not stop when his king had called him, Sumantra could always say that he had not heard the king calling him! Thus Rama told Sumantra to lie. This was because the purpose of the avatara would be fulfilled only if Rama went to the forest. If Sumantra had turned back the chariot, how could Ravana have been killed? So Rama Himself encouraged the telling of a lie, because the situation demanded it. Likewise Sita too told a lie, when it was necessary to do so.
So in this matter She was only doing what Rama had done.