It's a long story...

Meaning

Indicating a story that would take too long to explain fully.

Examples

• John: Why are you so late?
• Alice: <b>It's a long story...</b> Let's just say I had some unexpected travel issues.
• John: Oh, I see. So you won’t have time to explain it right now?
• Alice: Not really, no. <b>It's a long story...</b> Maybe another time.