After watching the song so many times I also think it illustrates the journey of their relationship. Asad singing towards the end is him finally accepting her and reciprocating. Then it's all rainbows and butterflies for them.
But I'm confused at the quoted... when did her gaze shift??
At the end the scene just fades into darkness while both are staring at each other, Asad holding her hands to his heart. She is still looking at his eyes - from his left eye to his right eye then fades.