
Don't worry he is not the ML, but he is her first love. From my knowledge of reading different many manhuwas, mangas, novels and watching lots of anime, the archmage will most likely die protecting her or for her/in her arms. She would learn what heartbreak and sadness means for the first time and the ML (the prince) will appeal to her.
That's how it happened in "saiunkoku monogatari" (a manga/anime I recommend 100%)

x x S P O I L E R S x x
uhm actually the prince will marry alicia? the blond medical who is nursing kasia? it was a political marriage, alicia also knew that the prince likes kasia but her doesn't get angry and turns to a villian lol, later on the prince will start to appreciate alicia. ernon will not die :)) and the ML is ernon not the prince

WHAT?!! is that true??? Will alicia actually become a villain? If thats true then I knew she was one because of the look she gave the prince when they first met but then her attitude became nice?? But Im pretty happy that ernon is the ml because he needs to have a nice future for he is an absolutley adorable guy that needs protection because of how he is abused but the prince I swear my heart beats for the two, -I mean my heart beats for all them but- Ehem Ehem My heart is in turmoil ٩(๑❛ᴗ❛๑)۶
Apparently the arch age is the ML and that's fine but I don't want the Prince to be the 2nd ML I just want him to be happyyyy