I have cause to rue the day...

Meaning

Expressing strong regret about a past event.

Examples

• John: 'That investment didn't pan out as expected.'
• Alice: 'I know. <b>I have cause to rue the day</b> I made that decision.'
• John: '<b>I have cause to rue the day</b> I agreed to this. It's been an utter disaster.'
• Alice: 'Things haven't gone as planned.'