Lyric discussion by alf1053044 

Cover art for Firefly lyrics by American Music Club

This verse always gets me:

Tell my why you don't sleep anymore Tell me what you sit up all night waiting for Are you waiting for loneliness to paralyze Are you waiting for Sister Midnight to unleash the tide

I think "the overwhelming dream that's killing us" is that the object of his affection (or a friend) is pursuing something that's driving them apart. The "overwhelming dream" could be a career, or could be drugs or something else harmful, as in something out of a bad dream.