Lyric discussion by douglasson 

Cover art for White Foxes lyrics by Susanne Sundfør

of course it's about relationships, typical situation when somebody waits for someone to see their feelings, but by the time they receive a response, a feeling back, they are already tired and don't want what they wished for in the first place yet Susanne Sundformanaged to wrap this situation up in such delicate, powerful words and the way she expressed that exhaustion, that anger inside: "I wish to God that the earth would turn cold" and the chorus the line "And my heart would forget it's made of glass" probably means this: it pains her that she has become callous (as to stop feeling sadness), but if she stopped thinking of it, she would be ok with her "glass heart"

My Interpretation

or, let me correct myself: she was waiting for the other's response to her feelings, and, well, she got it, but she feels that it's shallow and insincere, thus "poses" and "pretty tulips" and broken heart.

"And oh I wish to god that the earth would turn cold And my heart would forget it's made of glass"

glass. means it's so cold that she stops remembering to have any feelings whatsoever. because glass breaks easily. you are correct, she wants to feel numb. having an opposite of love, which is indifference.