Strange pretty much has no idea how to explain this. Why do you do the things you do, well because he's him. How else would he answer this? He certainly doesn't have enough insight into his own personality to give Steven a good explanation. Strange mostly knows his flaws because people & prophecies helpfully spell them out for him.

"To be fair, other people also act poorly whenever we've got a terrible situation," said with a pointed look at Steven. Talking about you, Steven 'cries at the slightest hint of emotional distress' Universe. "And I've no reason to lie to you about anything."

Steven's frustration is making Strange a bit frustrated as well. He frowns slightly, leaning back on his elbows.

"Besides, I didn't know that about CY-Ren," Strange points out. "Nobody knew much about anything those first few days."