I would think he’d blame his father, but the mental image of Jaina screaming FUCKSHITDAMNIT is too beautiful.

“FUCKSHITDAMNIT” Jaina yells, as spell misses and a bookshelf catches aflame.

Arthas just stand there, staring at Jaina with a mixture of shock and fear, oblivious to the conflagration behind him.  

I fucking love you Bark. Come give me a fucking hug.

Annnnd I just made myself have feels by imagining the same thing happening in the Halls of Reflection as the players are fighting Falric and Marwyn (Arthas and Jaina are fighting, Jaina FUCKSHITDAMNITs and Arthas momentarily just stops.)