Ok so .... Spoiler
They're going to make lots of flower with the same color and depose them to every one in the dorm so people thinks its a prank.
Bad things are going to happened at the ball, the prince is going to be more of a threat from now on. The MC is gonna be genuinely afraid of him for a moment and nobody will do shit, they'll think MC is playing hard to get for the prince.
Everybody knows who MC is after that and most hate her, there's like the group of the prince's marriage candidate who will have a talk with her. Basicaly they're warning MC that she should stop this game whith the prince and stop approching him.
After this ( i think or may be a little more later in the story ) MC and Riol are gonna spend time at Riol's family house to avoid the shitty prince.
Also, I know that at some point in the story ( I forgot when exactly ) MC's best friend is gonna be filled in on what's going on, she'll stop being a prince's fan and start bashing him too. There's a bonus chapter about her where she can't read romance stories anymore 'cause she finds the main guys creepy in it now. XD
Actually, I read the novel on novel update
https://www.novelupdates.com/series/the-noble-girl-who-finds-a-nerdy-and-plain-guy-moe-thinks-that-the-arrogant-prince-is-in-the-way/
But here's the spoiler forum if you just want spoiler
https://forum.novelupdates.com/threads/the-noble-girl-with-a-crush-on-a-plain-and-studious-guy-finds-the-arrogant-prince-to-be-a-nuisance.111963/

please give me spoiler