The different ways people interpret the folklore love triangle are sooo interesting (and all of them are valid not trying to say otherwise!) but to me it’s very clear that August & Betty are the high school-era songs whereas cardigan is the retrospective of an older Betty (in her 20s or 30s). To me the narrative reads that Betty & James got back together after his August summer when he kissed her in the garden. They stayed together through their early 20s (~to kiss in cars in downtown bars~ what high schooler do you know who is doing this?) But THEN he left again (this time for school maybe, or a job or something. ~stepping on the last train marked me like a bloodstain~). It’s like, James tried to change the ending the day he showed up in her garden, and it worked for a time, but the ending was always inevitable even from that moment in high school. Peter losing Wendy. Leaving like a father, running like water. Betty knew that at the time (~I knew everything when I was young~) and got back together with him anyway, and now she’s left bleeding, chasing shadows of him.

Also I do interpret the last lines “i knew you’d come back to me” as them finding their way back together for a second time in the end (not about him showing up in her garden), but I think it can be left open-ended as her just being wistful.