The thing is Ibu was tricked herself, she really does love Aramiya, but is a dumbass, they told her if she tricked him like that, and he waited, it would mean they would get married.
Also the Aunt wants to pretty much sweep that incident aside cause she pushed Aramiya to actually go out and wait for Ibu in another town, and not only that, Aramiya got tricked 3 times, which is why he ended up changing schools, the Aunt felt so guilty about it, she started paying for both of his cellphones so that he would not get fucked over again.