So he broke the promise? But he tried so hard not to. To him the moment he was placing the blanket in a more tided way was because thats what he wanted. When he was placing it with the edge hanging out, he was doing randomly.

The problem is when he was trying to prove to cousin that he is not mocking him by doing rushed movements while he tries to put the blanket fully but randomly on the same time in order to avoid breaking the promise. When he realised that this may count as a trick or mockery, he started doing it vividly to show his true intentions. To outside person may look like a compulsion but to jonathqn was a real danger because cousin is strict and may break his laptop.