The fact that you are in possession of someone (in the role of primary carer) does not mean you always should be, or indeed that the point will never come when they decide for themselves that you are no longer going to be.
That 11 year old is a person. She is entitled to have a relationship with her father that is separate to that of her mother's relationship with her father.
the fact that her mother adores her, that she is well cared for, that she has a loving and supportive family already, all this is actually superfluous to her wish to live with her father.
If you don't make some allowances towards this, what will happen is this.
She will turn twelve, her father will make a petition in a court of law for residency to be changed, CAFCAS will ask your DD where she wants to live, and she will say she wants to live with her father.
The court will then decide that LEGALLY he has all residency rights and responsibilities, and YOU will get the visitation she decides to turn up for.
IS that what you want to happen? or would you like to start listening to what your daughter wants and not what you think she should want?