This seems a little clearer, but I think it would help to start either with a fu

This seems a little clearer, but I think it would help to start either with a full verse or chorus of the song, maybe set apart like this:
Making plans to travel ’round the world
Said we’d always put each other first
Old love songs we used to play to
Funny, now I hate you
The reason I think this might work better is seeing the lyrics in context may help understand what the meaning was in the original song. The individual lines can be quoted as you put them in context with your interpretation and especially in the context of your relationship.
And as I said before, if you want to include your breakup and the former relationship in this essay, I really think we need more information. Do you remember the marriage essay we read at the beginning of the semester? She never mentioned her husband’s name (I don’t think) but she mentioned very specific moments that contributed to our understanding of her feelings. Right now, the relationship you reference is so generic that we can’t really understand the feelings you say the song brings up for you.
Imagine your relationship was a movie or a tv show. Consider telling us about one or two specific scenes, with details, that illustrate certain stages in the relationship, especially those that relate to the parts you mention (the hopeful planning in the “honeymoon” phase, for instance), and connect them with the lyrics you have cited.
Also I’m curious: if the song’s lyrics have enabled you and your ex to express yourselves “without speaking,” how do you know his understanding of the song is the same as yours? Maybe I’m not understanding what you mean by that, or maybe that requires added explanation.
you can speak upon a relationship you have had these are the details that the professor is asking for.