What is wrong about that person?

I once was in a relationship with Ms. Litson. Things were OK, I guess. But not before too long, I could see that I could not keep up with her. Things were slipping. I couldn't bear this, it brought me to my knees. Sometimes I thought that nothing was wrong, she was laughing, singing, trying to keep thing straight....and then I woke up. I'm blabbing too much; I went to great lengths, but in the end I confess I was blind. I'm gonna miss Mary.

When I heard the story above, I obviously understood something wrongly. What?

Massive Hint:

• enigmatic-puzzle tag maybe? – Barker Aug 1 '19 at 20:40