I do like how all of their plans backfired to be honest. It was karmic in a sense, but I wish the other girl learned to make her move
Keep in mind that a reoccurring theme of this work is how pettiness and vindictiveness leads to people not getting what they want, and in order to get what you want, it's better not to think of these convoluted plans to get revenge, but to be honest with yourself and others. Hence why all the characters are miserable, because it's their own faults at the end of the day through the actions they took, with the one who is least guilty being MC, who is the one who started this entire plan to get revenge by pretending to go out with someone else.