the real reason she gave up on harry on all the completed routes was because after the kiss at the start she decided not to be proactive and wait for Harry's move.I did not saw this part where is it???
but yeah i dont think that this part is strong because we dont have a build up with aya but I think the kiss part at the start that is not impented yet has alot of potential. Imagine a part where aya and harry are datting and are happy maybe hear luca bang laura next door maybe aya wonders how he can keep up this long but cuddels with harry,they go on dates, aya cant believe her luck with harry and how happy she is .... and the player has a emotional bonding with aya and than lose her slowly like a slowburn/ntr game this would be so hot to slowly lose her completly after beaing the happiest man in the world.
the choices in these routes are to ignore aya, you don't give her a chance so she gave up.
the scene where luca blackmails aya with a nude photo is what he meant, it happens in the normal route.
that blackmail was just small part of the reason she gave up and left, it was mainly because he ignored her.