Hot take: Ayu might overreacting with the level of response, but also isn't in the wrong. On the contrary, Kon is being unreasonable.
If your partner says "I don't mind if you go" and you tell them explicitly that you are coming straight home, but then you end up going but don't tell them, that's kinda just being disrespectful. It's essentially reneging on a verbal promise to be with your partner, but not telling them and just leaving them in the dark.
It's not controlling to be lonely when your partner ends up not being at home where they said they would be on Christmas Eve.