Max, what about really exploring other types of sensual and satisfying physical contact with her? Sensual hugging & holding one another in eachothers' arms for extended periods of time, lying in certain positions together, massages, etc... She may feel much more comfortable with this because it's not actual 'sex', yet such close contact and intimacy can be extremely rewarding... Maybe she will find that she will awaken something within herself that has been dormant for a while now, due to her past experiences...

Sex is not the end all / be all... In fact for males the pleasure associated with the sexual release is extremely short-lived - and then that release significant depletes us of our mental, sexual, and physical energy afterwards... I would venture to guess that the majority of people out there do not sufficiently and thoroughly explore the type of physical contact that I alluded to in my first paragraph because they are way too focused on simply just having 'sex' and getting their short-lived reward (climax)...

Since your GF is currently not wanting or willing to pursue regular sexual relations - this might be a great opportunity for both of you to explore different manners of experiencing physical intimacy and pleasure... Give her an hour long massage with no expectation of receiving anything or any 'favor' in return - just simply because you care about her and you find it rewarding to make her feel good...