I can't remember what chapter they got together in but I remember that the Prince was going to confess to her at a party but before he could Irene blackmailed him into not talking to Charte (I think that's how you spell her name) again.
Anyway, for the longest time the Prince thought he killed his older brother but then he found out it wasn't his fault. He confessed to Charte and they got together, and then Irene poisoned herself to frame Charte, but they found traces of the antidote in her body, so they looked around her room and found the poison and antidote, so when Irene woke up she was kicked out of the Palace.
Then the Prince looked into his brothers accident a bit more and found that he was assassinated by the Empresses orders and they took her to trial
She gets imprisoned and (a thing I forgot to mention was the development of an iron boat that Charte was in charge of was finally finished) Charte talks to the fifth Prince and makes it clear that she is rejecting him, and as a final thing to give up on her he requested a tassel thing that women make and give to men during this ceremony. Anyway it's really ugly but she gives it to him anyway and makes another one for the Prince but didn't get a chance to give to him during the ceremony so when the pro 've saw the tassel his brother has he got a little pissed
That's the latest chapter

I stopped reading at some point, and I need an update. Did the Female Lead (the one who was isekai’d) got with the crown prince? I’m confused by the latest chapter, someone explain to me T-T