She wants to marry a kohein and hopes her husband will pass away before she is a gerusha?
Nice.
The solution for this, is for him to give her a passul get against her will. Because, most passul gittin are enough to passul her from kehuna.
And this way he is not oiver on the cherem, since it wasn’t a kosher get.
For example, he could give a get that says that she is divorced, but is not muttar to anyone else. And like the asmachta: ????? ?? ?????? ??? ?????