My kids are 12, almost-9, and newly-7. The last few days of June, we met my parents halfway to drop the kids off with them for a month at Camp Grandma (my parents live in the country, about 17 hours away). In the week or so before that, I couldn't get my son's attention long enough to get him to complete a task. I was getting frustrated. Then I heard the 9-year old say to her little brother, "You can't ignore mom yet. We're have a few more days before Camp Grandma, and then you can ignore her."
When I heard that, my first thought was that nobody was going to Camp anything, I wanted their rooms cleaned before supper, and holy crap, nobody better ask me for ice cream money. All of that happened in a second or two, and because of my extremely hurt feelings.
And then I realized, from a kid's point of view, things are pretty much that black and white. But not permanently.
They've been there awhile now. I get texts from the middle one, the one who hurt my feelings. "I miss you! We had fun today but then we had to help with the lawn." I got one from the 12-year old, too. "We have a lot of chores. I'm having fun, but I want to sleep in the morning." In their world, they have fun or work. Not both.
In their world, they have to listen to the person in front of them or not, and only FOR NOW. In a week, they have to listen to someone else. The person in front of them is invisible, out of sight. They are still learning about impermanence, for one thing, the very thing that delighted them about peek-a-boo when they were babies. "I see her. I don't see her. OMG, I SEE HER!!!"
Your daughter has freedom at your house -- there's a lot of freedom in being in a safe place with people you know love you unconditionally. She doesn't have the words for that yet. And when she's at her dad's, she may not remember this.
But I can guarantee you, when it's time to come home to Mum, her little brain is going to be excited. "Yay! Love!"
Because Dad's love means someday it goes away, so that isn't love. Love is Mum.