Emma was quick-witted and always found ways to save herself. She didn't want to die, no matter what. She wouldn't give her enemies that satisfaction. When she knew Therius refused to marry Yldwyn right then right there to save their plan, Emma quickly thought of something.
She realized, if they fought against the royal guards, they wouldn't win because they were outnumbered. She took the fall for Therius so the royal guards would arrest her and Therius could kill the king.
When it didn't work, she was quick to pretend that she was pregnant with Therius' child to buy them time. She knew the king wouldn't want to hurt his grandson's child.
Therius rarely showed his expression in front of other people. So, when Emma lied and claimed that she was pregnant with his child, the young man didn't look shocked. That's why the people in the chapel thought Emma was telling the truth.
King Cassius raised his hand and ordered his guards to arrest Emma.
