The lyrics posted for this song are mostly incorrect. I'll break down my interpretation verse by verse, with the corrected lyrics:
Verse 1:
Lost in Space a bubble drifting
into a place where planets shift and
the moon's erased
it's features lift in the glare
Verse 2:
But I'm the stuff of happy endings
though mostly bluff
belief suspending but close enough
for just pretending to care
The protagonist is the bubble drifting in space. Like a bubble, the protagonist is hollow. She is aimlessly floating around in space (a metaphor for her desolate life), completely disconnected from the world around her. And the chorus makes it clear that she doesn't even care. The functioning part of her is "mostly bluff."
verse 3:
Well, she's the face and I'm the double
who keeps the pace and clears the rubble
and, lost in space, fills up the bubble with air
The protagonist is still physically present, and yet she is completely removed--just floating through life. Her physical presence/self, the one that goes through the daily routine (while she is still mentally disconnected) is the "double who keeps the pace and clears the rubble." In other words, it's the (minimal) part of her that functions in society.
bridge:
You split like a cell
and then cannot tell
the line from the parallel
The bridge highlights the previous image of a disconnected person. The protagonist is fragmented into two parts, her core self (which is disconnected, and apparently, extremely fucked up) and the part of herself that functions. The images of the split cell and parallel lines in the bridge are perfect in illustrating this fragmentation of the protagonist's personality, to the point where she (or perhaps those around her) can't tell which one is real.
The lyrics posted for this song are mostly incorrect. I'll break down my interpretation verse by verse, with the corrected lyrics:
Verse 1: Lost in Space a bubble drifting into a place where planets shift and the moon's erased it's features lift in the glare
Verse 2: But I'm the stuff of happy endings though mostly bluff belief suspending but close enough for just pretending to care
The protagonist is the bubble drifting in space. Like a bubble, the protagonist is hollow. She is aimlessly floating around in space (a metaphor for her desolate life), completely disconnected from the world around her. And the chorus makes it clear that she doesn't even care. The functioning part of her is "mostly bluff."
verse 3: Well, she's the face and I'm the double who keeps the pace and clears the rubble and, lost in space, fills up the bubble with air
The protagonist is still physically present, and yet she is completely removed--just floating through life. Her physical presence/self, the one that goes through the daily routine (while she is still mentally disconnected) is the "double who keeps the pace and clears the rubble." In other words, it's the (minimal) part of her that functions in society.
bridge: You split like a cell and then cannot tell the line from the parallel
The bridge highlights the previous image of a disconnected person. The protagonist is fragmented into two parts, her core self (which is disconnected, and apparently, extremely fucked up) and the part of herself that functions. The images of the split cell and parallel lines in the bridge are perfect in illustrating this fragmentation of the protagonist's personality, to the point where she (or perhaps those around her) can't tell which one is real.
Anyway, that's my take on it.