But for my mum it’s not about control. It’s about her being a bit of a softy and looking at the dog’s big pleading eyes and thinking about her tired old bones and wanting to indulge her with a warm and cosy place to sleep. And thinking that surely I won’t mind just this once...
And disregarding your explicitly expressed wishes in the process... That is the issue.
Out of interest what’s wrong with the chocolate thing?
Is it that you think your children will expect chocolate from you? That they will be spoiled? Is it that the grandparent has gone against your wishes and therefore clearly doesn’t respect you? Is it their teeth? The sugar content?
It doesn't matter what the reason is for having the boundary - the issue is the grandparent having gone against the parents' wishes. It might not be an issue for you. But for some people it is and that boundary should be respected whether or not the person understands or agrees with it.
What if your boundary was, "I don't want my child spending the night in the house with a man I don't know"? And what if that boundary was ignored? And what if it later transpired that that man was a convicted child sex offender?
Or what if you were vegetarian? And when your children were at their grandparent's house, they fed your toddler sausages? It doesn't matter that sausages aren't the work of the devil. Or that the grandparent's aren't vegetarian. Or that grandma is just a bit of a softy and looks at their grandchild and thinks, "what a shame that they've never tasted a sausage"? You, as the parent, have said, "no meat".
Or what if you have said you don't want your 8 year old left in the house alone and the grandparent decides they're only popping down to the shop for milk and will only be out of the house for 10 minutes and they're sure that the 8 year old will be ok on their own for that time?
If we trust people to look after our children, can we not let them make some little decisions even if it’s not the one we would have made?
The point is that most people generally do trust people to make small decisions regarding their child even if it's not one that you would have made yourself. However, that has to be within the boundaries. If someone has been explicitly asked not to do something, then they shouldn't do it.
Take it away from children for a moment. I have a boundary of fidelity in my romantic/sexual relationships. I wouldn't give a second chance, and never have. What about if someone ignores that boundary? Some women will walk away at a kiss; some women would forgive a one night stand; some women would work through an affair. What about that boundary?
What if you've asked your husband not to grab your boobs when you're cooking dinner and he continues to do it? You say he's not being controlling - he just fancies his wife and wants to touch her. Does that make it ok? That's a boundary.
It's interesting you talk about people you 'trust'. Boundaries are about what you are personally willing to accept in your life, in your relationships etc. I decide whether and how much I trust someone based upon their ability to respect my boundaries.
I wouldn't trust someone who repeatedly ignored my boundaries. That is the point. If I can trust someone on the small stuff (e.g. returning home on time/not giving chocolate before dinner etc) then I know that I can trust them on the big stuff (e.g. not exposing them to child sex offenders/leaving them in the house unattended/feeding them sausages when we are vegetarian) because I know they are someone who respects my wishes whether they share or agree with them or not.