The condition Ereshkigal proposed was actually nothing major.
"Although the Underworld is destined to disappear, I am the Underworld Goddess. Let me fulfill this duty until the very last moment."
In other words, Ereshkigal could form a contract, but she would not leave the Underworld for the time being or follow Luo Zhen. Instead, she would protect the Underworld until it disappeared.
If Luo Zhen was willing to accept this condition, Ereshkigal would form a contract with him.
But before that...
"The surface world can only be left to you for the time being."
This was a contradiction Ereshkigal had no choice but to resolve.
She wanted to help the humans on the surface, but she also wanted to protect the Underworld until the very last moment. These two wishes conflicted with each other, making it difficult for Ereshkigal to choose.
If Luo Zhen could help Ereshkigal resolve this contradiction, then she could form a contract with him.
Ishtar had the most straightforward opinion on the matter.
"You really are such a pain."
That was probably Ishtar's most genuine thought.
She wanted to help humanity, but also wanted to remain here. It had to be said that Ereshkigal's wishes were truly contradictory and troublesome.
From the perspective of the free-spirited Ishtar, it was indeed troublesome enough.
Of course, Ereshkigal was aware of that herself.
"I know I'm a very troublesome goddess. I've always been this way. Put nicely, you could call it persistence and determination. Put harshly, it's just indecisiveness. But I really can't bring myself to abandon the Underworld."
Otherwise, Ereshkigal would not have watched the situation on the surface while fretting helplessly in the Underworld, eventually committing all sorts of contradictory acts: borrowing Ishtar's body to help Luo Zhen in various ways, forming an alliance with the other