Rhaenys had the opportunity to fly away in House of the Dragon Season 2, Episode 4. Many say that her death wasn’t necessary. Well, there is a good reason for her turning back, and you could see it in her face.
After the fall of Sunfyre, both Meleys and Vhagar were flying away from each other. Rhaenys could have headed back to Dragonstone. However that would have been a cowardly move. While Snfyre went down, Rhaenys needed to see if Sunfyre and Aegon were dead. She also needed to make sure Rook’s Rest was safe. It meant she had to turn back and attack those on the ground.
Rhaenys’s inaction had already led to this in House of the Dragon
On top of that was Rhaenys’s knowledge that this could have all been avoided before. Rhaenys broke Meleys out of the Dragonpit at the end of the first season. She came through the floor at the coronation and chose not to attack. Daemon even said during the Deason 2 premiere that Rhaenys could have prevented the Dance of the Dragons.
This surely played on Rhaenys’s mind. If you watch carefully, Rhaenys was ready to fly off. There was a hint of regret at not preventing this when she could, and there was sorrow as she told Meleys to attack again. She knew it would be a loss if she ran into Vhagar again, but this was something she had to do. She needed to see it through, even if it meant her end. She came here to protect Rook’s Rest, and she died trying.
Had it not been for Vhagar’s surprise attack from the side and straight for Meleys’s neck, there is a chance that Rhaenys could have got away. It just wasn’t meant to be. We got to see how much Aemond thinks ahead. He’s a master strategist, with little care to anyone but himself and the power that he can gain.