The posion does matter, yes he would still have resented her, but that does not compare with the things he did to her under the influence of the poison, Tia says it herself before they know about the poison, that he always treated her coldly but she didn't knew why when Jieun appeared he started treating her with deep hatred. the difference is the extreme of his actions. Without the poison I don't think they would have been happy either is just that he wouldn't done all those horrible things.
Is not like he only likes her now because of the rejection, their entire relationship has changed, now he actually knows her they have shared a lot of time together getting to know each other, and he trust her now before he thought of her as a cold woman who only cared about the tittle of empress everyone thought like that.
Also about the God yeah I don't understand either, Vita's actions don't make any sense for now. I hope that will change later.
Someone should really yeet that God to oblivion. They're terrible at their Job
So if in another timeline Ruve wasn't poisoned at all but because of his inferiority complex wouldn't he still hate Tia? If she kept her original goal of trying her hardest to become a good empress because of the prophecy he'd still treat her terribly and use Juien against against her right? No matter how many timelines she goes through if her original goal is the same Ruve would always be jealous and hateful and that's not because of poisoning, he's held those feelings since childhood.
He only likes Tia now because she rejected him and focused on herself. So does the poison even matter? It seems like no matter what happened to Ruve if Tia never stopped acting like a puppet his feelings wouldn't change.
I'm just rambling but what is God's goal? Jieun wasn't able to take over after Tia and do any good for the country so why is she a chosen child and what was her purpose? Tia was never a chosen child until her second life when she decided to live for herself. Does the God want the fall of this empire or something because none of the chosen people marry Ruve and create a peaceful utopia after or defeat the bad guys. And why even give Jieun the choice to interfere in Tia's second life. Couldn't Jieun have her own separate revenge timeline?
What's this God doing?