feminine subject

Heaven is a place on earth with you
Tell me all the things you want to do

I think the darkness of the song is represented on two fronts

I say you the bestest
Lean in for a big kiss
Put his favorite perfume on

There seems to be some promiscuity in that the sexual interaction with someone leaps to a reference to another.

And when she sings about the epic sense of love giving life meaning and then says 'now you do' it seems like it's much more related to an internal object then an actual person:

It's better than I ever even knew
They say that the world was built for two
Only worth living if somebody is loving you
Baby now you do

It is like we'd have an object narcissist who is darkly looking for sex with others to bolster her sense of personal attractiveness mixed with a subject masochist who is choosing to love 'death' (as a sense of self-pity and detachment from the world).

video game represents both these aspects in her revenge infidelity to her boyfriend (who'd rather play video-games) and detachment from the world into an artificial world.