Welcome!
The comments here are mostly from once active JWs. Well they maybe hard to accept, the comments are honest and are based upon knowledge and experience in JW doctrine and practices.
While some have advocated assisting your girlfriend to escape the JW religion, in all actuality, unless she realizes for herself that the JW religion is not "The Truth", there will always be potential that she will return to it even if she does not practice for some time.
While you or anyone else could present endless evidence proving the religion to be wrong, most JWs will only ignore the information and will resent the presenter for attempting to offer it.
With regard to JWs being married to 'non-believers', there have been endless WT/Awake articles and sermons on the topic of marriage, particularly regarding not to even consider dating a non-believer. One statement made at a circuit assembly, compared a JW kissing a non-JW spouse to kissing a 'corpse' since JWs believe that non-JWs will be exterminated at armageddon.
While there can always be examples presented where a JW & non-JW marriage was successful, those are uncommon. While a mixed religion marriage may always present a challenge, the JW religion is most often assured to create a problem for reasons already mentioned.
While you may hope that it won't be, I think in the background, you realize your girlfriend's religion will be a problem in your relationship otherwise, you wouldn't be here asking for input and support.