To the OP and his Girlfriend,
I understand where both of you are coming from. I also understand the "cultural" Muslim versus the teachings of Islam and I know that the cultural Muslim is very off putting from actually learning about Islam and loving Allah, and the teachings of the Prophet. There's also a slight difference between being an 'atheist' and being 'agnostic', sometimes people tend to confuse the two.
Anyhow, when I a non-Muslim, I had Muslim friends who didn't follow Islam, but followed the "Cultural Muslim", you know the one who is a walking contradiction (if you know Islam), and the one that you can sort of hang out with, but you end up abhorring Islam and all Muslims. I was like this before, I used to detest Muslims and detest Islam, because I learned Islam WITH the cultural Muslim, not the follower of Islam. Anyhow, I had friends from all backgrounds, Turkish, Afghani, Pakistan, Egyptian, etc. Since I am a lover of foods.. I went over to their homes a LOT to eat and stuff my face with pastries from all over the place, plus all of their moms really liked me. I was a NON-Muslim, but I wasn't a drinker, an alcoholic, I didn't use drugs, I called my mother and I let her know where I went, whom I went with and when I was coming back. I respected the elders, I helped around the house, I had the normal temperamental tantrums of a teenager of course. Just because I was not a Muslim, did not mean that I was a walking devil, or someone horrible absent of morals or decent thoughts. Each different place had different interpretations about "Islam", in some places I felt a sexist kind of thing about Islam, where the women were sort of the maids, the servants. I remember going to a friends house with my mother and father, they were also friends with the family. We were invited in, and the father sat by himself while his wife worked in the kitchen and served my mother AND father food. I was a little repulsed by having the mother do all of the work, while the father sat his lazy bum and just looked at his wife like a maid... I knew they were Muslims, so I automatically assumed that Islam was teaching this to Muslims... then I saw another family, friends of ours as well, I saw the mother and father walk out of the grocery store and the WIFE was carrying, LITERALLY carrying everything, and the husband was so LAZY. My mother commented and she was appalled, we also knew they were Muslims.... Everywhere we saw, was this repulsive behavior of MEN, NOT acting at ALL like men, but acting like the owners of the cattle that pulled their groceries, made their food and served at their feet. We were always appalled at seeing this. I don't think I have ever see my mother carry something, or serve food to a strange man, LET alone invite a strange man into our home and have my mother serve a strange man food, while my father sits like a lazy person and watches.... and we were not Muslims. However, the image that I got from the "cultural" Muslim, the one who calls themselves by the name of Muslim, but doesn't follow the teachings of Islam. They didn't even pray, the daughters didn't wear hijab, etc, etc, but were "Muslim" by culture, by birth and not in anything else.
My idea of Islam changed when I went overseas to a Muslim country. When I saw Muslim men CARRYING the groceries, while their wives walked by their side. When I saw Muslim men caring for their women like princesses, queens and not like maids or cattle. I remember going to a friend's house, and she was married. However, I never saw her husband at all, lol. Unlike my previous experience with Muslim families in North America, where I had the unfortunate circumstance of actually meeting the male relatives (I dislike talking to guys....), I didn't have to pass by this horrible awkward experience with her, because we were secluded and in our own little world. I don't want to say that she was also not a cultural Muslim, but she wasn't just "muslim" by birth, but she ascribed to many things that I had never really seen or experienced with other muslims in North America.. I felt a different sensation, not a repulsion, not an abhorrence or the desire to detest Islam or Muslims, but a desire to learn, to REALLY want to learn and it was her genuine love for Islam that motivated me, not this 'cultural' thing that is so superficial and really absent of meaning.
To the OP's girlfriend, she posted here, I know your current position is one that comes from learning about Islam from the "cultural Muslim", because you were forced, coerced into following things without actually believing them. I saw that you don't want to marry a man that your parents choose, or marry and cook and clean and be a 'maid'. In Islam, you don't have to MARRY someone that your parents choose, you have a choice and that choice is protected. You can say yes or no, it is up to you. The reason why some parents choose is because it is easier for the marriage to go through. The parent choosing is a CULTURAL thing, otherwise if it was inscribed in Islam, I would be single for the rest of my life, because my parents will never choose a spouse for me. (Even though I would personally prefer it, I know my mom has good taste

) You are also not required to be a MAID, in Sharia law, it is the responsibility of the husband to provide for this, or to help if he is financially UNABLE to provide.
I remember I took a class on Islam in undergrad, well several. One of the weeks was about the rights of women in Islam and it was my FAVORITE week. Women are both protected AND liberated in Islam. Our financial rights are INSCRIBED in Islam, the min. rights of property, etc. are clearly outlined as at least a base upon which agreements between the husband and wife can build on, but at least there is a MIN! In other kinds of religions and in secular law, there is no 'min' kind of rights that protect the women to the same extent as those inscribed in Islam. Marriage between a Muslim man and a Muslim woman is preferable because in Islamic law there is a DEMAND on the husband to keep certain responsibilities. In Islam, it is the husband who is endowed with the financial responsibility of maintaining the home. The wife is allowed to work, but she is not required to contribute a SINGLE cent of her earning, while the husband has to contribute ALL and provide (help clean, or hire someone who can clean for the wife), clothe the children, shelter, food, etc.
I know this is a huge post and maybe it will not be read, but I wanted to let you know that there are certain things that you shouldn't confuse between Islam and the cultural Muslim. Take apart the things that your parents have presented you as "Islam" and compare them with the Quran, the Hadiths and scholars about issues and open your heart, your mind and clear any negative thoughts you might have about Islam as presented in the news, through posts that you might read about people who confuse 'culture' with Islam and relax. Islam is SO BEAUTIFUL and when I converted to Islam, I became a productive person, with meaning in life. I became focused, concentrated, and I did so well in my school and my studies, I was more in tuned with myself because I let go of things that were so superficial. Yes, I am still human and unfortunately I judge... but Islam and constant reminders help me and rectify my negative thoughts that I can have against people and helps me to tame them. There's an inner conscious that sort of springs up and tries to redirect you. I found clarity and goodness in Islam, but I would have never opened up my heart to it, if I would have secluded myself to learning about it from the 'cultural' Muslim, who is Muslim by birth, but not a follower of Islam by heart, that is who you should seek to find and perhaps both of you can make that journey together.