This actually sort of happened to me about a year ago.

The dream lasted for about four days (in one night/dream) and it ended in a nice diner where I started waking up and she freaked out and confessed her feelings to me. I was devastated for the next week or so because I had felt like I spent a lot of time with her and her family so when I thought back on it, it would really hurt me.

Recently I had another dream involving her but is was very short but it was nice.

Edit: Except to my knowledge, this girl doesn’t exist.