So, in the end, Endermask comes to the realization that in order for his lady to wake up , he has to die. So he sacrifices himself so she may do that. That was acceptable to me.
The main issue I had was that the entire series had Enz and Iremy have this tension of a relationship and after Endermask takes his own life, Iremy decides that she's going to travel the world to look for a way to resurrect him leaving Enz and the majority of the rest of the crew behind. The epilogue takes place 6 years after the final battle and I was just displeased with no Enz/Iremy connection. You would think that seeing the struggles and hardship Endermask went through she wouldn't want to follow in his footsteps.
It may have been because I stopped reading for so long before finishing it, but I don't really understand the Iremy infatuation with Endermask. There was always a hint of her being obsessed with him even after the first timeskip where they separate.