It was confusingly written.
So, the father is Kei?
She married the other guy anyway but she's still seeing Kei while leaving her daughter to her mom?
Why the hell wouldn't she get together with Kei? They aren't related anymore since their parents divorced. Especially if he's the father of her daughter.
I understand the husband, but what right does he have to keep them apart? She doesn't love him at all, she just used him.
It's a real clusterfuck.