My girlfriends mom

Hello

So the story is like this, ive been dating my girlfriend for about 12months now, i see something very special about her and i love her very much. I know that she loves me too, and our relationship is great. We used to be best friends and then ended up in a relationship. At the moment she is studying abroad, so we have a long distance relationship that has now lasted for about.. 6months. We see each other every semester, around 3-4months just skyping, texting and trying to forget the distance. A problem that i face, is her mother. She is very protective, and she always want her daughter to finish her studies and then think about getting a boyfriend, but also she always had in mind that her daughter would get a boyfriend from the same ethnicity. You see, she is from china, and her mother wants her to have a Chinese boyfriend (we live in Holland). Also her mother does not know that we are together, she thinks we are really close friends (which we are too).
Dont get me wrong, im a person that hates to lie, but i'd do anything for our relationship to be as smooth as possible, i dont want to risk her mother not letting her to see me again.

Ive met her mom several times, and she really loves me, she calls me son and cares about me. The problem is, that hearing my girlfriend saying that her mother does not want her (my girlfriend hehe) to do anything so i would "fall for her" etc, and uses always the word "friend" when she talks about me makes me hurt. I dont know why her mom cant accept me, she says that she wants her daughter to be happy, and she is happy with me. I even make her study better as i try to motivate her, and not take up her study time, my girlfriend always keeps telling me that i am good for her. I know that by any chance that i would never disrupt her from her studies, so thats no argument her mother could use against me.

I dont know what to do now, im trying to think positive thoughts, but it is hard when knowing deep inside that her mother might never accept me.

Yep it's a cultural thing. Moms put so much pressure on their kids to marry within their race. But in the end she is the one who has to make the decision. If she chooses you then she dishonors her family.
There is more to this, if you don't know the language and culture then you will feel left out at family functions. If you don't know the history then you can't communicate effectively with her family. Further, the older relatives will frown upon you. Are you ready for all that?