Realizing that someone who once loved you loves you no longer is like getting the measles: go through it when you're young, and you'll probably get a mild case.
If it happens for the first time when you're older, it can be devastating.
It can be fatal.
Imagine that he's the first one you ever fell for; he might not have been the first one to kiss you, but his was the first kiss to matter. You can still taste it. You remember the shock, and the softness, and the lingering of his mouth on yours. It was the first time you ever thought: "I want to keep this. This is mine."
He loves you. You can hardly believe it. He sends you little notes where he writes your name over and over again. He calls you first thing in the morning and last thing at night. Words, rolling dark as waves at midnight, wash over you; his voice is heavy and slow as he tells you that you alone understand, that you are the only one.
You can't believe it. You try to resist, not having been born yesterday, but it takes all of an instant for you to be swept off your feet. Swept off your feet, you lose all control over where you're going. Not that it matters. The undertow pulls out the ground away and you drown. Willingly, entirely, without a last gasp or a hand raised to save yourself, you drown.
You are in over your head. You know it and still it doesn't matter. Not as long as you can stay immersed in him. You grow accustomed to this life, where shapes are never quite sharp and light is always refracted. Other voices that once called to you grow faint. The gestures you make are careful and labored, designed to keep you steady. They keep where you are. Which is near him. Which is all that matters.
The day he stops loving you or, to be more specific, the day you realize he no longer loves you, you can't breathe.
The hurt is unfathomable. No one survives this. It would not be possible. You dive further down. The weight almost crushes you. It doesn't matter. Somewhere people are waking up, going to work, having lunch and dinner, sleeping through the night. You think of such a life the way a child thinks about castles and dragons; you can imagine it but you know, somehow, that it isn't real. Such a life does not exist except in imagination. Maybe it did once. But not anymore.
Ignorant of your belief that time cannot pass, time passes.
Changes that you once fought against, tides that you swore did not exist, begin to move you. Very nearly against your will, if you claim any will at all, you are lifted and borne forward. The anchor you cursed as too weak to keep everything in place begins to seem like a gift, so easily does it break once you kick it away from you. It never was what kept you motionless. That was only your own wish to stay still, the way prey freezes in the gaze of the predator. That kind of stillness isn't quiet or safe; it is negation. Playing dead.
Moving again, you can no longer pass for dead. Re-entry isn't easy. The abyss was dreadful and easy. Being on your own two feet is not easy. Movement demands balance and choice. You thought you could get away with not having either. Thought that if you crouched down low enough, the current of change would pass over you. The sand on the ocean floor is not so low that it remains unmoved by change. How could you escape?
You go forward. You must. Even if you don't know where you are headed.
Like emerging from out of a bottomless sea or waking from a long illness, nothing is the same. Landmarks are different. You orient yourself along new lines. Maps or medicines, proffered by kind hands, might not be useful but you know they are important.
You accept them with thanks, and understand that such gestures matter.
Things start to matter. They always did. Now you remember.
Now you know you knew it all along.