Amy's poem is a short, plain-spoken address to someone who has hurt the speaker. The opening lines pin everything on "you": this person is both the "cause" and the "reason" for a flood of feelings the speaker never names. That vagueness feels deliberate. "All these feelings" suggests emotions too tangled or too big to sort out, whether hurt, longing, or anger.
The second stanza shifts from blame to disappointment. The person "could have changed" and "could have been different," and even said they could. But the speaker "never thought you would," which hints at a quiet, tired resignation. They seem to have expected the promise to fall through, and perhaps that makes it sting more.
The mood is sad and a little bitter, but restrained. The short lines and simple repeated phrasing sound like someone speaking carefully, trying not to say too much, while the hurt shows through anyway.