Someday

"Tom's first superhero girlfriend was Someday.
She had red hair, a compact frame and two superpowers: an amazing ability to think big and an unlimited capacity to procrastinate. Someday had never used her superpowers in combination until one Sunday morning, three months after she'd started dating Tom. They were lying in bed. Someday was staring at the ceiling.
'Imagine it all,' Someday said.
'Hmm,' Tom said. He kissed Someday's freckled shoulder.
'We're going to get married and own a home. We're going to have kids ... ' she said.
Tom stopped kissing her freckled shoulder. He stopped moving his fingers. They could hear the refrigerator.
' ... someday,' Someday quickly added.
The moment she said it, she shrank. It started happening all the time.
'I'm going to paint the bathroom ...' she'd say.
'Don't say it!' Tom would yell.
' ... someday,' Someday would say. She'd shrink.
Every time Someday used her superpowers in combination she shrank, and every time she shrank, she shrank by a little bit more. When they'd met in March, Someday stood 5'4". By May she was 4'7". At the end of August she was 11". By October she was sleeping on the cotton from a bottle of aspirin.
The last time Tom saw her was in December, through a microscope. She stood next to a dust particle.
'Someday, I miss you!' Tom told her.
'Someday you won't,' she said.
She disappeared."