What defines when you expect one thing but the opposite happens?

This situation is defined by the concept of irony, particularly situational irony, where there’s a stark contrast between expectations and reality. It often occurs when an outcome is incongruous with what was anticipated, leading to surprise or even humor. This can stem from mistaken assumptions, unforeseen circumstances, or the unpredictability of life. Such moments highlight the complexity of situations and challenge our understanding of cause and effect.