Here's a SIMPLE, yet effective, solution that I've not seen posted yet (which I am quite surprised of): /ignore

Simply have her do a /whois on his nickname. Everything after the Whatever@, put an ignore on. So say his address is:

IamDaStalker@Wherever.somelink.net

You would do:

/ignore *!*@Wherever.somelink.net

Hope this helps in a great way for you and her!