I should also state that, unless her and her parents are completely oblivious to this, he does not mark at her apartment or her parents' house.
This I also found wierd. Pepper also does not like my female westie. She was even in heat a few weeks ago when my fiancee was down visiting with him and he wouldn't even go near her....not that we really want puppies right now, but he growls at her constantly when she gets anywhere near him and her being in heat did not affect that behavior towards her at all. She loves him and wants to play and craves attention from him all the time but he won't pay attention to her
Poor girl....she just want some and he won't give it to her, lol.