Things have developed with Sekai and Makoto. From the outside, it seems like Makoto is still involved with Kotonoha, however his relationship with Sekai has accelerated. While, Sekai knows its bad to keep lying like this, she can't turn away Makoto. Gradually, Makoto starts avoiding Kotonoha by not answering if phone...
He should have just told her...I don't know how he thought it was ok to string her along like that. I know it is hard to break up with someone but jeez! But I suppose at least Sekai and Makoto are passionate about each other.