I am not surprised for numerous reasons. For one, it is common for people who have a connection to the Path, to have difficulties with their partners, with whom they have a kind of karmic link, which does not translate to shared understandings of spiritual matters.
For another, it is common for men to have difficulty in getting women to relate on a cogitative level. Women trend to relate emotionally, and all the talk of intellectual insights into how we operate, fall of deaf ears with women - they are seeing a completely different situation.
Then for another, your task, as with all of us, is to translate your cogitative understandings in an affective way. You are trying to reach across from your understandings to another person's understandings. It doesn't work that way. You have to apply your understandings to yourself for a such a long time that you forget them, and they become a part of your natural behavior. Those understandings have to sink down into your body and personality. Instead of reaching across to the mind of another, you inculcate the comprehension into your being, then link to the other from your being, not your comprehension. Your girlfriend need know nothing of your mental insights, as what she wants is the direct end result, coming from your emotions and behavior, not your mind.
Lastly, for the reason that you don't yet seem to understand where she is coming from. You understand that she doesn't get where you are coming from. This is unfortunate because she sounds like she is wanting to make an effort to have this relationship work somehow - that is worthwhile. Not everyone is so keen. Would be a pity to lose such a friend.