You and God had a very healthy and happy relationship. But... You didn't tell him you were half demon. When he found out he was angered and sad that you didn't tell him. And when See (God's friend) noticed his anger, she asked him

See: "Alright, what has you so out of sorts, my Lord, you clearly got more on your mind than Humans and Demons and Hell's Overpopulation!"

God: sigh "What do you do when someone you love lies to you about who they are...?"