Sita was a very devoted wife, so much so that you will rarely ever find her parallel. She was always very sweet to Ram. Ram was everything for her. Unfortunately, some people mistake her calm nature has her weakness. But the reality is just the opposite. Let me post some contents from Valmiki Ramayan to prove how brave she was.
1. Ram informed Sita that he had to go into exile and Bharat would be made the king. He asked Sita to stay in Ayodhya and explained how she should conduct herself. Even devoted wife Sita immediately rejected Ram's suggestion. If Sita's devotion for Ram had been because of any kind of cowardice, then she would have always done what Ram said, even if it displeased her. Being in Ayodhya when her husband was in forest was highly displeasing to her. Therefore, she did not agree to Ram's suggestion that she should stay in Ayodhya. This shows Sita's strength to speak for herself.
Ram explained very clearly how many difficulties should would face in the forest. As per Kaikeyi's demand, only Ram had to go to forest, not Sita. Living in forest for 14 years was indeed extremely difficult, specially for a lady like Sita who had always lived in comfort. Any weak-hearted woman would have feared living in forest. But, for Sita, the difficulties in forest were nothing compared to the pain she would face on knowing that her husband was in forest and she was in palace. Ram gave various arguments as to why she should not go to forest. Sita, in reply, gave various arguments, as to why she must go to forest with him. In fact, she even explained how she would enjoy living in forest. Ram explained forest as a very dradeful place and Sita explained forest as a very beautiful place to live in if she had Ram's company.
Ultimately Ram had to agree to take her with him to the forest.
There is one thing very remarkable about the way Sita argued. Often when two people disagree with each other, then they shout and use some harsh words. Sita was pained on knowing that Ram wanted to go to the forest alone. She had tears in her eyes. But, she did not should or use any harsh words. She was sweet and yet firm - a quality, which is rarely witnessed in an argument.
Will post more.