To clarify, she wasn't actually trying to jump tho. During this time of her contemplation, she was already aware that dying won't make her return to her world (since she said that she already died once but still came back even after not trying to intervene with the flow of story). Yes, she felt betrayed and disappointed but she wasn't attempting during that time. Hes was even the one who assured Kael that she wasn't attempting to jump (after Kael pulled her from the balcony and hugged her).
Kael was the one who misunderstood the situation. Of course as someone who had felt the same situation, he would definitely assume that.

Spoiler
Spoiler but i really hope they didnt change the part when Hes trying to jump of the balcony when she know that Kael vote for keeping Diana on the throne. That part when she feel betrayed and just done with the whole novel thing (she still think that she is in a novel and that she wanted her fav charac to have happy ending) and hoping that when she die she will get back to her own world.
Its that kind of feeling when u got super disappointed with a story us just want to dropped it. And when Kael saw this he turned back to his depressed self again cuz he cant accept losing her lol... That moment is my fav part so i hope they dont change it