I think that…Sasuke himself showed his change obviously right after his last fight against Naruto ( After all the time, Sakura has always helped and forgiven Sasuke)..This was when Sasuke realized that he not only had loved her romantically but also he felt a love more deeply than their bonds.His feelings is so consistant. And in my opinion, it linked to the sentence “I’ll see you soon” of Sasuke afterwards.