Hyacinthos, Lover of Apollon

It is known that Apollo had many male and female lovers, most but not all ended in tragedy. However, his love for Hyacinth was way beyond anything. When the Spartan prince Hyacinth died in an accident (variously by accident or envy of the Wind God), Apollo was so struck by grief, that he pleaded to the Gods to be turned into a human, so that he would one day be reunited with his beloved Hyacinth. He even went to his Uncle Hades, pleading to kill him, so that he would at least in death by the side of his Lover.

But Hades denied it, and explained, he, Apollo, was Immortal, and this could never be lifted from him.

I know of no other tale when a God loved a mortal man so much, that he'd rather be human or dead that seperated from Hyacinth.