First of all, people use icy treatments to punish and/or control others. If it doesn't work on you, then why fret about it?
She may be trying to find someone else to keep them so she can stay out later......or maybe not, IDK. You have a couple of choices. You can text her to see if you are on the same page about later, or you can go about your plans as usual if there's no response. Did you give her a cut-off time to let you know for sure? You know her, so is she assuming by what you told her that yes, you will keep them till 7:30?
Keep it simple and don't make it harder than necessary.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
