That's exactly it thought, if he leaves then any chances of him having his foot in the race of succession will be destroyed. He's staying because he needs to manage his side from the background while the other two princes hash it out front and center. While those two cause more trouble within the kingdom by pulling up each other's bad deeds, like how the second prince's most loyal guard was arrested and the first prince's border security plan failed, the third prince (our boi) needs to continue his duty as nota prince but as a Duke and care for the people within his dukedom. Thus raising his reputation slowly, yet amazingly higher than the other two. Also, Evony wanted to go alone because she wanted to grow as a person make her own decisions, and learn about the world with no one with prior knowledge of the world outside her home. Sorry for the long wall of text (￣▽￣)
Just go w her ? Didn't u just come back from being away??