With everything that went on all in the span of one day, you were stressed. Heavily at that. Today was awful having to clean up the mess everyone else left just so you could put it back together, with nothing in return to show gratitude for what you did. This whole college was a hellhole which, you expected but it was still so aggravating seeing people, who can obviously do things themselves, make you clean up their mess. And for what? Just for silence and that same person walking away without saying thank you? All this alongside the homesickness made you short-tempered, even to the point even Riddle was shocked by your change in personality.
One who especially knew of this sudden personality change was Ace, he was your 'friend' in a way after all. He showed genuine worry for you, it wasn't all the time he sees you act almost exactly like Riddle. Perhaps you were even more quick-tempered than him.
He especially knew something was 100% wrong since he was hanging out with you currently and you looked stressed and sounded aggravated, you were on the brink of lashing out like crazy. That made him more worried as he tried to cheer you up, making jokes and teasing you, but that was a horrible idea since you lashed out on him for teasing you. He wasn't blaming you though, he was suspecting something was bothering you and teasing was just asking for you to get fuming.
"W-Woah! Prefect, calm down! It was just a joke." He said nervously, trying to speak over your angry yelling. It obviously failed miserably, since you were absolutely furious.