Did I Break her Spirit?

My oldest daughter is 7 years old and is a great kid.  She's smart, outgoing, polite, able to interact well with kids and adults alike.  She plays just like any other kid, and has fun playing with her friends.  Most of the time she gets along well with her siblings.  She is very aware of rules and follows them exactly.  Everyone always says that young kids need structure, so when she was a toddler my husband and I set rules for her and she followed them to the letter.  As she got older there were more rules, but for the most part they all come down to the basic principles of keeping our kids safe and healthy and having respect for others.

While I love knowing that if I tell her something I only have to tell her once, sometimes she gets so serious about the rules that she doesn't understand that exceptions can be made and not everything is black and white. She has become the master of sulking.  For example the other day she and her younger sister were playing with one of those little Barbie pools.  They were playing with it outside as I knew they would end up splashing a bit, so rather leave the mess out there.  After a bit of playing they were also pretty wet so I said something along the lines of , "no more Barbie pool, time to clean up for dinner".  To which she started sulking and said, "You mean we need to throw it out?"  No I didn't mean that, I suppose I could have added the words "for today", but come on kid do you need to take me so literally?  This is just one of countless examples and it happens multiple times a day.  She has always been a very focused kid, which is great when focus is what's called for, but that doesn't mean that every word needs to be taken so literally.

She has also started enforcing my rules on her siblings, which bugs me.  For breakfast I give them fruit and milk to start with while I prepare the rest of their mean (these days usually pancakes).  In the beginning to get them to eat their fruit I wouldn't give them the pancakes until the whole banana or at least half an apple was eaten, but now they are usually pretty good about eating the fruit so I don't really enforce it anymore.  This morning, she asked for a banana and her sister wanted an apple.  When the pancakes were ready I gave them maple syrup in a bowl for dipping their pancakes in and put it between the two of them.    She immediately took the maple syrup put it on her place mat and declared that her sister couldn't have any because she hadn't eaten any of her apple.  I told her that was not up to her to enforce and to share the syrup.  She spent the rest of the breakfast sulking, and sure enough after her sister finished her pancakes she ate her apple half.

The main problem is that when she gets in to one of these funks, they last quite a while and she has a hard time getting happy again.  I've tried to teach her how to put it behind her, move on, not sweat the small stuff, step away for a minute and come back happy, find your happy place, all that stuff.  Doesn't work.  I try changing the subject and usually I get a few minutes of grumpy answers and then she brings up what she was sulking about again.  I'm hoping this is just a phase and as she learns how to control her emotions she will learn how to do the things I just mentioned, cause otherwise the poor kid is in for a life of disappointment and grumpiness and I don't think I can take that.  The hard part too is I can already see that change happening with my 5 year old.  She definitely has a bit of the middle child syndrome, but I don't want to the same thing to happen to her as well.

I wonder if I'm to blame.  I know personality is based on nature and nurture, but did all our rules break her spirit or was this just the natural evolution of a very focused toddler who thrived on routine.