Besides, what's the point of this theory?
I already explained that.

Let me add some other theories important to the whole thing:

I always get the impression that Square intended for Jill to be married with Sazh before the flashbacks.
She started to behave like a bitch and he decided he canīt stand her anymore.He left her.
He hated her so much that he pretended to everybody who met him afterwards that his wife was dead.