
I'm confused, so was it Shuli who died or the crown prince's mother?

Actually, this is the second timeline because after we finish seeing the cardinal backstory they show us his thoughts about the situation and what role will FL play in his plans in future. So to explain it in both timelines Theo's mother is dead, in the first timeline Theo doesn't meet the FL and catch feeling to monopolies her, in both timeline the cardinal sees the FL as a treat to his plans to get full control over the household and nobles but now because FL in second timeline she acts different because she knows the future he got an interest in her so he plans to become allies or enemies based on what FL would choose.

What was the relationship between the duke and fake blonde?

Isnt he the one "taking care of the refound princess" tho for a stranger she only meet a few months ago.. she is trangly close to him..
Got a feeling she was "missing" while secretly hiding at the DUke's place..
After all what better ruse to gain sympathy than to be the only gifted child of the emperor who "vanished" and then returned with all the skills of a trained nobel daughter.. to one up her powerless sister..
I swear they'll use anything to make the ML the ML, first it was time travel to the future and now it's turning young with intercourse