Not only that i also remember that past Theo didn't tell the whole truth to Martina and that he somehow betrayed her and it was all connected to their relationship and their love as far as i know. The past Theo didn't truly and wholeheartedly love Martina as I understood it. He was using Martina by making her fall in love with him and trying her to break his curse because there was a rumour that the people like Martina (her clan) could break curses. Later on he grew fond of her, we can see that but it wasn't true love and maybe that's why they couldn't break his curse and he chose to die by being killed in so called "riot" even tho it was all arranged. And that's why Martina is so heartbroken because she finally understood what was going on and that's why she can't open her heart so easily especially to the present Theo which looks exactly like the past Theo. That's my conclusion, idk if I'm wrong but yeah.
So basically Martina didn't know this was the same curse, because Present Theodore was said to turn into a beast. That's why she freaked out hearing that guy who returned the portraits mention how one of the earlier dukes died, which was exploding as a beast. That was how she connected the dots. Plus, Past Theodore didn't show signs of turning into anything as far as she knows because he secluded himself and she killed him per his order/request.
Now, the confusing bit where people seem to think Martina knows how to cure it when no one had any record of how to cure the curse besides the Shitty Brother, Waldo, is that the Dukes family DOESNT know how to cure it and she barely learned it in the present. The Duke family would just have the current head married and have an heir before he would succumb to the curse and die in the end in case yall forgot.
Also cmon people. Literally seeing Present Theodore everyday triggers her trauma for Past Theodore. Lol. Past Theo was literally her last hope and light and she took his life per his selfish request. Ye, they had doodoo communication and she loved him, BUT the point is that she couldn't forgive him or give in to truly love him at the time due to all the political strife and then his illness. You see how angry she was with him. Fast forward to Present Theo and she has lingering feelings for Past Theo on top of not quite being "in love" with him just yet- just growing more fond of him. Now, she's not just freaking out with what happened to Past Theo, but is now panicking for Present Theo.