When you write a song you are likely enough thinking about some particular set of circumstances. But that's just the starting off point. It's a way of getting in touch with some feelings that are relevant to other circumstances as well.

Interpreting what a song (or a poem, or a picture) is about is something that other people have to do as well, and their interpretations and the way they apply it to other situations are just as valid.

Often the first understanding you get of what a song is capable of being about comes from other people.A wise songwriter who is asked what the song is about will answer "You tell me what you think, and then I'll tell you what I think." And in that sense anyway I'd think Neil Young is a wise songwriter.