How were the Tears of Love and Hate formed? El Nido legend seems to have forecast their formation, as well...
Lynx's Hate, Harle's Love
Lynx: The enmity is growing! The only thing pure in this world is enmity!
If I remember correctly, this quote is shortly before (or when) he actually shatters the Tear. His emotions leave it with hatred.
The Tear of Love is a bit more complex. When Lynx succeeded in acquiring Serge's body, Harle could have continued with him and eventually stolen the Flame, but she didn't; rather, she betrayed the Dragons' wishes and rescued Serge, a human, instead. She probably would have continued to betray the Dragons had Serge not wanted to finish his quest. As such, Harle was forced to betray herself and her love for Serge. So I'm quite sure Harle's love formed the Tear of Love.
From: Theory (Objects)