Character Analysis
Even though she's only in one scene, Lady Bona plays a big role in causing allegiances to shift. She's King Lewis's sister, and when Warwick comes to France with the promise of a marriage to Edward, Lady Bona is excited. She's heard about the English king and thinks it would be awesome to be his wife. She might even have a little crush on him.
If this seems weird to you, don't worry. In Shakespeare's England, marriages were often part of bigger political pacts between countries. It was a way of joining two countries together, so that they could share weapons and troops and not fight with each other. Warwick suggests marrying Lady Bona to do just that, and it all seems settled when she and King Lewis agree.
But then Edward randomly marries Lady Grey behind everyone's backs. Lady Bona's totally embarrassed, and the little slip-up costs Edward dearly. Warwick and George change over to Henry's side because of this, and King Lewis follows them. It was a totally stupid thing for Edward to do, and it was all because he couldn't keep his hands off one woman while he was waiting for the other one to agree to marry him. Does that tell us anything about Edward's ability to rule?