I read this story in a single-author collection of short stories circa 2002--2004. The book was a new edition trade paperback, taken from the new acquisitions shelf at a public library in southern Indiana. I assume it was categorized as SF/F, or else my teenage self likely wouldn't have picked it up. I have the impression that it was the author's debut collection, but I could be wrong about that.
The story is in a literary, magical-realist vein. It's about a husband and a wife in a world where there's some kind of epidemic that results in people's skin gradually becoming harder and harder. As the disease develops, the people begin to float off the ground. The woman gets the disease and as it progresses it becomes apparent that her skin is growing into a spacesuit (with a clear bubble face-mask and everything). Once the spacesuit nears completion she starts to float, at first just a foot off the ground, but rising day by day. Soon the pressure starts to crush her against the ceiling of their bedroom, so the man has to take her outside. He tries to rope her down to the ground, but she is pulled up with stronger and stronger force until he had to cut the rope so that her legs won't be ripped off and she shoots up into the sky. I remember the ending felt tragic and elegiac in that high-literary sort of way.