Clark knew, somewhere deep down, that he could be... cold, towards Dima. His attention was focused on Jonathan, because he was Kryptonian, he was his heir, he was the one who would protect the people after him. Dima? He lacked Clark's genes. He was an ordinary child.
As children, Clark gave them equal amounts of attention, but as Jonathan grew older and his powers manifested, all of Clark's attention shifted to him. So yes... he ignored Dima quite often. But he thought he knew his child well!
He'd been training Jonathan to fly all day today, and he was sure Dima was in his bedroom. He was surprised when the front door clicked open, and Dima walked inside. Clark frowned as he stood up from his seat at the table. "Dima? I thought you were home. Why didn't you tell me you left?"
Clark walked up to him, crossing his arms over his chest, looking down at him sternly. "It's late. Where have you been?"