Lyric discussion by gfun 

Cover art for It Don't Move Me lyrics by Peter Bjorn and John

I think the chorus goes:

"What used to keep us warm Is slowly getting colder"

It makes more sense that way, anyway.

I agree with those who say it's about a bitter breakup. The key line is: "You don't move me no more...and I don't even mind." No regrets, no nostalgia, no fondness.