Facebook message was never delivered?

Ok, so I sent a message to my friend two weeks ago, eventhough we aren't friends on facebook we stay in contact. The message was sent, but never delivered which is odd because she and I both have messenger on our phones and we're both really active on facebook. Now she also deleted her skype a week earlier too. If she muted my messages, if she did would it still say my messages were delivered instead of sent even if she were online?