Just a little ficlet that popped into my head one day about Don, Betty, and their crumbling marriage. Despite how the summary might make it sound, this story isn't about Don's infidelities, but about their family.

Thank God that Gene is still too young to understand what's happening between his parents, much less ask them questions about it. Because the questions that Don gets from Sally and Bobby are more than enough for him.

"Then why are you going?" Sally asks him, and the hurt and anger in her voice kills him. Don takes a deep breath and tries to reassure her – telling her that he'll still be her father, and he'll always love her – but halfway through his fumbling response, she gets up from the couch and charges out of the living room.

Don sighs as he watches her retreating back. He should've known that Sally wouldn't accept his watered-down, kid-friendly explanation of why he's moving out. His daughter has always wanted to know the truth, no matter how ugly or complicated or sad it might sound to her young ears. If she ever finds out how much of his life has been a lie... God help him.

You should've been better prepared for this, he scolds himself. After all, Don knew, deep down, that one day he would be in this situation – separating from Betty and trying to explain it to the kids. He's known that it would happen for some time now, ever since that day with the watering can...

It was a hot, lazy summer afternoon, a few years ago now. It must have been a Saturday or Sunday, because he was home from work, reviewing plans for a new ad campaign in his study. Bobby was still just a toddler, and Carla was putting him down for a nap in his nursery. Sally was stretched out on the grass in the back yard, reading a book beneath the shade of the trees. She was so smart, his girl.

Don tried to focus on his work, but the heat made his eyelids heavy. Birdsong drifted in through the window of his study, which overlooked the back yard, and created a gentle hum in the background. He yawned and reached for the pack of cigarettes that he always kept on his desk. The lighter was halfway to his mouth when he suddenly heard splashing and giggling from the back yard. Puzzled, he got up from his chair and went to the window.

The first thing he saw was Sally's book lying on the grass, forgotten. Then his eyes followed her laughter and spied her on the back porch. Betty had left her watering can there, still half-full, and Sally had kicked it over and was happily splashing barefoot through the puddle. Her pigtails swung up and down as she bounced through the water.

Don leaned against his windowsill and smiled at the sight, proud of his daughter for finding her own way to cool off on a hot day. Sally had never seemed more creative or beautiful. He was thinking about running to get his camera when the back door swung open. Because of the angle of his window, he couldn't see Betty standing in front of Sally, but he heard her sharp voice.

"What are you doing?"

Don never forgot the look on Sally's face. Her smile disappeared, and the light in her brown eyes went out as she looked uncertainly up at her mother, trying to figure out what she had done wrong this time. She couldn't have been more than six years old.

It was just a puddle that the summer sun would dry out in no time, but to Betty, it was another mess that her daughter had made. Her voice was not gentle as she told Sally to pick up her book, go inside, and dry off her feet. Sally didn't answer, but Don heard a mighty bang as she came inside the house, and he knew that she had slammed the door shut with all her strength. It was probably all that the poor kid could do to keep from crying. And Don turned away from the window and began to pace his study with a bitter understanding in his heart.

Don knew that someday Betty would realize how many good reasons that she had to leave him. He didn't blame her for that. He drank too much. He cheated on her. Worst of all, he lied. He was not a good husband. But that day with the watering can left no doubt in Don's mind that she was not a good mother. He had his reasons to leave her, too – or at least, to not fight it when Betty finally saw what kind of a man he was and made him move out.

How could Don ever explain this to Sally and Bobby? He left their mother because of a watering can.