What is the song Bitter Green about?

The song is about a relationship turning stale, and both individuals involved seem dissatisfied by it. One partner's desire for connection is no longer being met; both are becoming increasingly aware of what the relationship lacks: emotional resonance, physical touch, shared interests, etc. As time is ticking by, and their time left in the relationship seems finite, it's becoming more apparent why things aren't working out - they do not share similar outlooks or goals (as symbolized by 'green' not being the other's color). With every new morning, the feeling gets more intense and difficult to deny, eventually forcing one or both people into making a decision to separate ways to be truly fulfilled emotionally and mentally once more.