I think Eliette deals with loneliness by helping people all the time. During one of the dialogues she was worried about what she would be doing if her help wasn't needed. So yeah, she's a lonely pie. Still, let's not forget that she is not a human. Maybe angels like her can't feel lonely or bored, because otherwise they would go crazy from endless existence.
Even if that decision would've been made, it wasn't for her to make it. That's what 1st guardians and kings are for. Once again, it was mentioned in the game. During their argument, Maryen has shown her concerns about switching positions exactly due to risks of new purification armies being made, which means that as a 2nd guardian Eliette doesn't have such power.