Romantic relationships in Avatar seem anachronistic/modern
For a show that is based on Ancient East Asian Mysticism, the relationships in the show seem very modern. "Boyfriend" and "Girlfriend" are very modern terms. Ancient days courtships are a prolonged affair where you are getting to know each other's family and community in preparation for marriage. But couples in Avatar feel like modern day teens and young adults.
Only Princess Yue had an engagement that seemed period accurate. Would Mai's parents allow their daughter to be that physical with Zuko considering they are nobles? You would think they would be engaged at least
The show even mentions that Water Tribe women can marry at 16 but outside of Yue, we don't see any other engagements that young.
Zutara would feel very period specific if it happened.