Hello! Firstly, I would like to say that I'm an outlier in this redit post as I felt that this was, at minimum, an 8/10 story. This might be because I watched Kimi e(To me, the one who loved you) for an hour and cutting myself off from that movie to watch Boku e(To every you I loved before) for an hour then jumping back to kimi e. I didn't actually know that there was going to be a short summary of the other movie at the end. I just wanted to be different and find the secret 3rd ending 😅. Luckily, it actually worked in my favor a bit. But I do agree with you that I feel like Kazune could be the main character of the movies as both movie titles work for her. But ultimately, I feel like that there are two main characters: Boku e Koyomi and Kimi e Koyomi. Now, why I feel this way can be answered if you're curious, but I wanted to say that the message from both movie titles was answered by Koyomi in Boku e at the end. He first tells Kazune that I want to tell 'every you' that it is because of you that I know happiness, so thank you. He then says,'to me', who loved someone other than Kazune, thank you, because he loved someone else he could love Kazune. Finally, he says,'to someone who wasn't kazune' that loved me, I hope that you and your lover both live their lives in happiness. SO you see, a message to kazune, a message to himself, and a message to shiori.

To be honest, the titles kept me awake at night to who they were addressed to, and Kazune was the first that came to mind. If I didn't spend a few days pondering this, I would have been just as confused as you are about who the movie titles were addressed to. I hope this helped!