Literary Elements

Metaphor

A metahor is present in the lines "When I close my eyes/You replace him/Wearin' no disguise/You erase him" to show the mental replacement the speaker has in her mind when she truly wants this person over another. The other person doesn't erase him, but takes over their presence in her mind.

Repetition

Repetition is seen in the lines "I wanna feel guilty/I wanna feel that it's wrong" are repeated multiple times throughout the song. Lizzy repeating these lines emphasizes how she wants to feel ashamed and knows that her feelings are wrong. Repeating these lines brings attention to her remorse.

Juxtaposition

Juxtaposition is evident in the lines "He is stable, you are deep," "Softer, harder, in between".  The contrast between the two people shows the difference between them. Stable Vs deep shows how the one person is level/reliable, but says you are more than that (deep/complex). Softer and harder and in between show that even their physical interactions are different.

Symbolism

"I wanna sing a different song" is a symbol for wanting to change and live a different life. It is seen that she doesn't want to feel the way she feels and wishes things were different. I think this line especially 

shows she wants to be free and live without stress.

Personification

Lastly, the line "You erase him" is an example of personification. This non-human quality is given to this person that isn't physically erasing him. It was made to show how this person affects her enough to replace this other person. This line is powerful to show that he doesn't erase him physically but in her mind he has that pull on her.