Added 5-12-22.
Sky was not having a good day.
It made no sense, really; the sun was shining, the birds were singing, and several of Oropher's projects were ripe for disrupting. But even so, something just wasn't right.
Galion realized it first. The prince left quite early that morning for a meeting, and the butler had expected to see the princess within a few minutes, but she never appeared.
Eventually he went to knock on the bedroom door—no answer. He tried again, then hesitantly opened the door. It turned out she was curled up under the covers with a pillow over her head, and when he asked if she was all right, she just murmured "Yes" and pulled the blankets up further. Not knowing what else to do, Galion left her alone and waited for Thranduil to come back, but when he checked on her again a while later, she was gone.
She showed up at Felrion and Kilvara's house next. Kilvara (the only one there right then) immediately realized something was wrong with her friend, but when she asked, Sky just shrugged and said she didn't know what the problem was, and Kilvara's attempts to cheer her up didn't have much effect. Eventually Sky said she was going to go look for Thranduil and left, declining Kilvara's offers to come with her.
Sky's search for her husband eventually led her past Oropher's office, and unfortunately, the king had chosen to leave the door open that day... and she had caused a considerable amount of trouble the previous evening.
Oropher called her in and was angrily berating her for her antics when something happened which had never occurred before.
Eithryn started to cry.
Oropher froze mid-sentence. While he had long dreamed that someday one of his lectures to her would have some effect, he had not meant for it to go quite this far. "Eithryn, I... I did not mean..."
And, of course, Thranduil chose that exact moment to come in. "Father, are..." He noticed his wife trying to wipe the tears off her face and was by her side in an instant. "Eithryn, what happened?" He turned on his father furiously. "What did you do?"
Oropher was nearly speechless. "I do not understand... She never cared before."
Eithryn sniffled. Thranduil crushed her to his chest, on the brink of tears himself. "Shh... Here, come with me," he suggested, staring daggers at his father. The Silvan elf nodded tearfully and let him lead her outside.
Oropher was left wondering what he was going to say when his son came after him later.