Law / Polish citizen raised in Cyprus, GF from Belarus. Would she become an EU citizen after marriage? Poland study. [5]

Dear Forumers i read quite a few Threads in the marriage section but none answered my question...

Here is the situation, it is a bit complicated so i hope that i explain it properly.
I have a Polish passport because my father is Polish but i was raised by my mother in Cyprus. A little over an year ago i met my Girlfriend who is officially from Belarus, we fell in love and we decided that we have to be together. We are both about to finish our Bachelor studies this year and we want to do a Masters degree straight away in Netherlands but here is the problem: I as a EU citizen am required to pay a tuition fee of about €1.500 per year and she as a NON EU citizen, has to pay €15.000 approx which is way too much and that stands on our way of studying together and being together in general since we both are young and not as rich. Considering that issue i got the idea of signing a marriage contract with her hoping that it would give her the same rights as me and she will be able to study with the same fees as me, problem is that i don't know for sure if this is how it works and how long will it take for such documents to be ready and so on. I am a bit confused and this is really important to us, if any one here has any information i will be extremely thankful if you can share is since i did a lot of research but did not learn anything.

Thank you all in advance :)