Ok, I hope this is in the correct category, apologies if not. 

When I was around 5-6 years old, I first began having a dream about a garden, with flowers (particularly roses), an old oak tree, and a weeping willow. It always seemed to be a nice day, with a clear blue sky. 
I'd be sat in it, and a girl named Ivy would appear.. She was not much doled than me and wore a dress with tights and a cardigan. She immediately would run over, and beg me to play with her, which I did of course. She also talked a lot, was there for me, and always said I was safe as long as I was with her. It made me sad when I woke, and (to begin with) I found myself often looking about for her, but never saw anyone like her.

These dreams recurred until I went into the next school, they got a lot less frequent, but still happened until I was about 13 or so.

Recently, I dreamt about the garden  again, only this time it was overcast, the flower beds empty, the trees bare.
Ivy wasn't there.

I'm wondering why the sudden darker tone to what was once (vaguely) like something out of a cute children's storybook or Tv show?