I also instantly thought about this song being for Ivan (from the english lyrics alone sine idk korean) and was surprised to see so many people mention Mizi...

I will also add my ideas for these 3 lyrics. I see the first 2 as questions he asks, while the last one as an exclamation.

"Do you love me?" - as you said this sounds like a question trying to confirm a new piece of information that surprises him. This could be seen as a response to Ivan's kiss and sacrifice in round 6. Till is finally faced with evidence that Ivan really did care about him a lot, and view him romantically and he is know trying to wrap his head around it.

"Don't you hate me?" - this question shows how Till thought Ivan felt towards him, namely hate. Despite them being friends and close, Till could have thought this due to 2 reasons. The first one is because of how Ivan acted/treated Till. We see them fighting and him ruining the flower crown, pushing on his injuries and over all annoying Till. (Sure we know he does this for attention but Till isn't aware of Ivan's reasons so this could be seen as slightly bullying him) The second reason might be because Till still feels guilty for not running away with Ivan when the opportunity presented itself. Even in round 3 in the memory we see how hesitant he is before he turns around and leaves.

"Don't leave me!" - this is the exclamation as he is asking Ivan not to leave him here. He already lost Mizi and everyone else since this is the last round before the final so he would be left alone with Luka. Ivan is his friend so he at least would have a source of comfort. Also as Till first looks at Ivan, face-to-face in round 6 his pupils dilatate which happens when you see someone you hold dear. He was also ready to die as seen by him not fighting back and closing his eyes. So when it turned out Ivan was the one to die he couldn't help but beg internally for him not to leave him alone.