Will Christian faith eventually come?

I'm assuming that your question is about the possibility of your becoming a Christian "in time"?  If this is so, then of course the answer is to the affirmative - this is indeed possible, and perhaps will occur.  On the other hand, it may not, and in that case you will simply continue as you are, pretending to be something that you are not.

Having said that, I'm wondering if the anxiety and fear of discovery is actually keeping you from being open to your girlfriend's beliefs?  Or even from realising your own? You say you have attended church weekly for a year, and have participated in Christian practices such as saying grace, yet you feel this "status" of "being Christian" is still out of reach. But you don't say you have rejected Christianity outright, so I'm guessing the jury is not out at this point.  Does this mean that you are hoping for a sudden revelation or lightening bolt experience which will convince you of the truth of Christianity?  Sometimes faith and belief happens that way, but more often it is a matter of acceptance of the precepts of the Christian faith.  

The fact that you are in love with your girlfriend and all that she is tells me you do not reject that "faith part" of her.  I'm wondering if part of the attraction is actually her Christian faith and values.  If this is so, perhaps this will be one way you could talk to her about what's happening within you.  Explaining that you are sincerely hoping for the relationship with God that she has, and that it seems to be eluding you up to this point, may be more beneficial than confessing to "living a lie", which is not entirely the case, as you have not rejected Christianity outright. There may then be an opportunity for your girlfriend to guide you toward a path that will take you to the acceptance of Christ that you have found so difficult to achieve on your own.

You will have to weigh up the alternatives - perhaps your girlfriend will be hurt at first and even feel betrayed, upon discovering your dilemma, but to continue as you are, fearing exposure and embarrassment when meeting her family members may be even more painful for you.

I wish you all the best with it.