It was his birthday today.

He spent all day baking a cake for himself because you were too busy with work to spend time with him. He made such a pretty cake... Just for it to get slapped to the ground by Diluc. He decided to yell at poor Kaeya and ruin his cake... Kaeya was so upset. He sat on the ground, staring at his now ruined cake. He started tearing up a bit...

Then you finally came home.