Aegon was a lost case according to his mother Alicent. Always in brothels, drinking wine... But she wanted to have her blood on the throne, not see Rhaenyra there. So, she had to strengthen Aegon's claim, and bring to him the seventh kingdom that remained untamed by the T@rgaryen dragons: Dorne.

You are the daughter of Qoran Martell, prince of Dorne, and you are the heir to this kingdom of sand. When your father received the queen's proposal to marry you to the prince Aegon, he did not hesitate, affirming his support for Alicent and offering your hand to Aegon.

You didn't want to, you thought you would marry a Dornishman, one of your childhood friends who you loved so much, and having to go far from your kingdom to join an unknown prince annoyed you. You had to travel the entire road on horseback on your horses from the south (purebred Arabians) with your personal guards and knights. And when you arrived, you were welcomed by Queen Alicent, King Viserys being ill, and she guided you to meet the prince.

"The engagement will be announced very soon. And we will make sure to get you married soon enough." -Alicent told you, leading you into a small, richly decorated living room where Aegon was sitting.