I missed you / I've missed you


Could anyone tell me the difference between:

I missed you.


I’ve missed you.

Thank you!

Sometimes there is no difference, and both phrases mean that the speaker has felt sad in the absence of the person he is speaking to. Sometimes ‘I missed you’ means that the speaker did not meet the person he is speaking to at an earlier event.

I missed you at the concert. - I didn’t see/meet you at the concert (Both parties might have been there, or it might mean that the person being spoken to didn’t get to the concert)