So, she must have out the curse on him pretty soon after he met Sakura the first time...probably as a direct response, since she was jealous/had a preschool crush on him that just never went away.
Cliche-fest this may be, but when the dumb moments are revealed with such good pacing, I can't help but enjoy it.
EDIT: Wait, from what we saw, the pervert friend is very much rooting for the yandere. Which means that when he exploited the curse, he was secretly wingmanning for her. It did and didn't work. Killed MC's chances with other girls, but didn't close the distance between him and Akaha.