Question Please help

Well, that certainly makes it urgent...😵

Same question will apply to her, can't she simply access the notifications to determine the app? This should be rather easy to determine the source.

Or, is this something that you are concerned about (and she is not)?
 
That is not a technical problem, rather it is a personal one.

If you are that concerned, I would suggest a conversation with your GF and not with a community of total strangers.

Good luck.