GL and I may disagree on this. But I think you need to keep pushing forward being able to spend time with her.
The more you back off, that more time she has with him.
I think you need to expect to be shot down here a time or many times. But what other choice do you have? Going dark? Won't work, and OM would love that. Cutting back contact? Again, OM would love that.
Like I said, you'll walk a fine line between white knight and stalker, but you have to do it. Of course, this is all my opinion.