plot twist !
you'll never see it coming !
I've been warily expecting Diana to get offed basically from the moment she started getting along with Leticia while also still being interested in Mikael.
She and Leticia are too friendly with each other and Leticia is too sympathetic towards Diana to make it a real rivalry - which would likely protect Diana from sudden assassinations narratively by turning her into a villainess - but she's still technically competing for Mikael. She may not end up dead, but she's been all but guaranteed a swift exit from the story (perhaps walked back to just abandoning this current effort and fleeing the palace) because the narrative requires that she not succeed with Mikael. One could point to the flash-forward obviously lacking her presence, but I'd argue this would be the case regardless of the fact we've seen that: the FMC getting along with Female Side Character (FSC) while "letting go of" the MMC to said FSC is easily among the largest death/doom flags I can imagine for an FSC in this genre.
The "seek your freedom regardless of the fear and shame" motif between the two just before the season ended is like slapping the reader in the face with the flag, and could either foreshadow fleeing or be mainly to make Diana's death more tragic. I do hope I'm wrong, because I quite like Diana and I would especially have liked to see a friendship develop more between the two very different lives she and Leticia have lived, but all signs point to Diana's exit from the narrative. If she vanishes entirely by fleeing or by dying, to the reader her survival is almost moot, and to the author (who will need her not competing with Leticia soon to progress to the next arc of the plot, whatever that may be) it is also basically moot.
For the genre, Diana has been written so firmly into the doom corner I'm not sure I've ever seen a character so doomed by the structure of the narrative itself... besides perhaps the retrocausal doom of a fictional obituary.
Now... if the author wants to eat their cake and still have it, we may see the swordfighting guy whose name I've already forgotten (sorry man) die and Diana survive, to add the tragedy aspect to the fear aspect that could still drive Diana to abandon seeking Mikael while not fleeing the narrative entirely (perhaps turning into more of a tutoring role for Leticia as her own role puts her on display in the ways that Diana would be more experienced with - but that's a bit wishful on my part and logistically speaking it's simpler to just write Diana out of the picture, and the drama of "Leticia out of her depth with nobles and saved by Mikael" is maximized by ensuring Diana cannot come to the rescue, which can be ensured most solidly by deleting her from the living).