It was all because of those damned shoes.
Glinda knew, deep down, that she really shouldn't have given them to that silly little girl. She had felt a pang of guilt as she watched her skip off down the yellow brick road, pigtails bouncing in blissful idiotic ignorance, with that stupid yappy dog at her heels. After all, Nessa really had told Elphaba she could have them, hadn't she, even if it was all those years ago.
She had even been on the brink of apologizing to Elphie and retrieving them... but then Elphaba had, in typical form, flown off the handle as soon as she mentioned the mistake, jumping straight into infuriated dismay before Glinda had even the slightest chance to mention that it had been a mistake; and her own anger that Elphaba had immediately jumped to the first possible conclusion pushed all thoughts of apology from her head. Guilt was immidtiatly replaced by indigence and the barriers that had begun to come down in the long missed presence of her dear Elphie snapped rigidly back into place.
And then Elphaba was gone, storming off in a huff, and the guilt came back... settling as a lump in her throat when she realized she'd just ruined what might have been her only chance. After years of separation, desperately trying to push out of her head the thoughts of glances and touches and stolen moments, she'd had her back, within her grasp... and she'd let her slip away again... all over a stupid pair of shoes.
And Glinda sat down and cried.
Now, walking across the dreary paths of Colwen Grounds, she had once again shoved Elphaba from her head. She was probably gone by now, back off to Oz-knows-where, for good this time...
But she wasn't.
Glinda, head down as she walked, looked up at the sound of another set of footsteps, and saw the familiar figure, swathed in black, hat brim pulled down as a shield against the water that had just begun to fall gently from the sky.
The walls Glinda had so carefully re-erected after that horrid afternoon shuddered and cracked... but they did not break.
She did not look at Elphaba as they approached one another, averting her eyes to the pitiful flora along the boundary of the path, tracing each sagging blade of grass to divert her mind from any other form of thinking.
She knew Elphaba would not look at her either... she did not have to look to know that.
As the two women passed one another, something shot through Glinda, deep inside her... as if Lurline herself had grabbed her heart and twisted. And she knew. She would never see Elphaba again. And the walls broke. She did not want it to end like this... not for them, after everything. Not over a pair of damned shoes. She flung herself about and cried a name into the rain...
But Elphaba did not turn. To Glinda it seemed that she did not even realize that it was her named that had been called.
The rain came down harder, mixing with the tears gently working their way down her cheeks. And quite suddenly, Glinda wasn't Glinda anymore. She wasn't a sorceress, or a socialite, or a public figure... or even a woman.
She was Galinda again. And she was just a girl... watching as the only person she had ever loved disappeared into the rain.
As she strode through the forecourt of Colwen Grounds, she crossed paths once again with Glinda. But both women averted their eyes and hurried their feet along their opposing ways. For the Witch, the sky was a huge boulder pressing down on her. For Glinda it was much the same. But Glinda wheeled about, and cried out, "Oh Elphie!" -Wicked, pg. 355
The Witch did not turn. They never saw each other again.