Ayu & Tomoya's break up

[Machiko]

I've tried searching AHS and googling but I've found no confirmed reason for their break up... — until a friend of mine who just so happens to be a TOKIO fan mentioned an interview he had read in which Ayu said BEFORE the break up, that she viewed (and always has?), Tomoya more like a little brother than a lover, thus breaking his heart, as he was already considering proposing to her (according to Nagase's stepfather), yet I can't find this said interview or heard about it or really any other reasons besides "abortion" or/and "cheating".

I was wondering if anyone here had any clue what I'm talking about or is it like general knowledge and I'm just a Bad&Ignorant Fan™?