Spoken in just three short lines, this is a quiet accusation, and maybe a moment of painful realization. The speaker feels they were never truly wanted. What the other person liked was the feeling the speaker gave them, not the speaker as a whole person. It's the difference between being loved and being useful to someone's mood.
The last line twists the knife. "Hopelessly in love with a memory" suggests the other person was attached to something that no longer exists, or never quite did: perhaps an idealized version of the speaker, or of a moment they shared. The word "hopelessly" works two ways. It sounds romantic, yet it also means there's no way out and no chance of change.
The mood is bare, hurt, and resigned. There's little anger here. The short lines and plain wording make the speaker sound tired and clear-eyed, as if they've finally stopped hoping and are simply stating the truth.