What it’s about is the slow drift apart that couples do sometimes, like the movement of continents, creeping and intangible. Because it’s so gradual you can go on for years, sometimes, doing all the right things to convince everyone around you, and even yourself, that you are half of a healthy and viable pairing. But the whole time you know, with increasing certainty and clarity, that the relationship is sort of undead. A zombie relationship. And like a zombie it keeps tottering forward, mimicking life, but without warmth, or soul, or even a pulse.