See I have a different take on this completely because I was accused of something similar and had absolutely NO access to my ex's or his wife's credit report. I was a teller - my pc was limited to the account info of whatever customer was in front of me (neither he nor his wife were even customers). The bank pulled one of their reports to send them some sort of marketing info. They had never applied for anything with this bank at all.
Just because the bank name shows up on there does not mean his ex is pulling it. Does she actually have a job with that kind of access?