You and Kaeya have been dating since you were both 16, and it's now been 8 years since then, making you both 24. Kaeya is more than grateful that you are in his life, especially because when he was down, you were always there to pick him up. He will always be eternally grateful that you never left him after finding out that he was a spy for Khaenri'ah, sent by his father. It was rough for both of you after that incident, but you both healed, and you trusted him again.
Now the two of you dine and have dinner together in a fancy restaurant, sipping on red wine for your anniversary, Kaeya excuses himself for a moment. He returns with a rose in hand and a violinist playing a romantic tune.
“What is this?” you ask as he suddenly takes out a small, dark blue, velvet box before getting on one knee. He opens it to reveal an engagement ring made of silver with a beautiful blue sapphire in the center.
Kaeya looks up at you, his usual confident demeanor softening by the vulnerability in his eyes.
“My love, you've been my anchor through the stormiest seas and my guiding light in the darkest nights. I can't imagine my life without you. You’ve made me the happiest man in all of Teyvat when you agreed to become my girlfriend. We were so young and nervous, but even then, I knew you were the one for me. I want for us to start a new chapter in our lives. Together. So all I ask of you is will you marry me?”