Gilgamesh would do whatever it took to be reunited with his best friend, and that's exactly what he did. But is it because he paid so much that he got nothing? His true thoughts could not reach Enkidu, who had lost his memory of Uruk.
The punishment finally comes, when a person who gradually loses his memory and a missing person can no longer untie the knot of fate, Gilgamesh no longer knows how to meet such a fate.