I'm putting the lyrics of Jpop songs I listen to in the context of Repeat in my head now for some reason (www)
An example I find particularly fitting is veil by Keina Suda (Fire Force ED1). I could interpret the whole song as a monologue by Euca (in the Repeat route). I'll try not to go through each line but only give some examples below.
笑えない日々を辿ったって (Even though I traced back the days without laughter): This could be Euca lamenting how however he repeats the days, there's just something he couldn't change.
あなたの言う希望だとか 夢に見た理想ならば どんなに冷たくたって愛してみせるよ (If by 'hope' you mean the ideals we dream of, I will love it however cold it may be): This line can have both a figurative (straightforward) and a literal meaning in the context of Repeat. The literal meaning alludes to how the presence of wishes is cold physically, but despite that Euca still loves those wishes)
どんなに繕ったって その笑みの奥を疑ってしまうだろう (No matter how I fix it, I will always second guess the meaning of that smile): However Euca fixes the timeline, he'll always second guess himself. Echo can be seen as the embodiment of his hopeful side, so that smile could be Echo's usual smile, seen in many of the Echo sprites, and the line is Euca doubting if he could do it even if he so wished.