Assuming he had access to a database with (lat, long, SIM) data, if she got a new phone he could just use the known (lat, long pairs) from the old sim and lookup to get the new sim. Then bam, you can get all of the new lat longs.

It’s impossible to avoid unless you simultaneously move to a new house / apartment when you get your new phone, and never bring the new phone to any previous low-traffic location you brought the old phone to.