Some stories don't have a villain. That almost makes them harder.

Sarah had asked her boyfriend, let's call him Dan, more than once. Don't leave the bedroom window open. Make sure the cat stays away from it. There's no screen, no barrier, nothing to catch her if she goes near the edge.

Her cat, Mila, was 21. Not a kitten. Not agile the way she used to be. Just old and gentle and entirely unaware that windows could be dangerous.

Dan said it'd be fine. Every time.

Sarah was at work when Mila fell. She came home to find Dan had only just noticed something was wrong.

Three days in hospital. Vets cautiously hopeful at first, no major fractures, no obvious catastrophic injuries. But then the x-rays showed what age had quietly been doing to her joints. Osteoarthritis, advanced. For a younger cat, the fall might've been survivable. For Mila, recovery would've meant weeks of pain with no guarantee at the end of it.

Sarah made the call. Let her go peacefully. Twenty-one years, and it ended on a vet table two days after a window got left open.

What's stayed with Sarah isn't quite grief and isn't quite anger, it's something that sits between them. Dan has two dogs he dotes on. Walks them, frets over them, the whole thing. And Sarah can't shake the thought: if it had been one of his dogs near that window, would he have been more careful? Would the warnings have landed differently?

She doesn't think he did it on purpose. She's clear on that. But careless isn't the same as innocent, and feeling unsupported is its own kind of loss on top of the one she's already carrying.

She said she can't see him the same way anymore. That's not a dramatic statement. It just sounds like the truth.

Have you ever had a relationship change because of one moment of carelessness? Tell us below.