I think you did a good job laying out your concerns and conflicts. You said that this is a struggle between your love and your life and you're not sure exactly which carries more weight; which, for you, is the higher priority. Being able to ask that question is in itself a very good sign as it means your mind is still open and you're willing to discuss.
So perhaps we can do something of a cost/benefit analysis:
The benefits of your relationship with this non-Jewish girl are obvious. You probably have already investigated and discovered that you're "on the same page" in your world views and attitudes. She no doubt also seems to embody all the qualities you admire and seek in a wife. Perhaps more, she might possess fine qualities you never before considered and seem now most desirable. From your current perspective, the existence of these qualities would seem important or even essential for the creation of a good and happy marriage.
Now what's the cost? I will guess that your relatives aren't thrilled with the thought of you marrying a non-Jew so there will be pressure from those quarters. This pressure probably will never disappear and might even become worse with the passage of time. Your career of choice might be threatened by this marriage (assuming you will need your parents' support for your higher education) and your very identity as a Jew and comfort with Jewish life might collapse.
Perhaps the greatest potential cost lies in the possibility that Judaism and the Torah are the legitimate, expressed will of God. For if it turns out that the Torah is indeed authentic (and, as you know, intermarriage is prohibited) then you've lost a whole lot haven't you? I believe that every Jew has the obligation to at least thoroughly investigate the possibility (and a good place to start is Rabbi David Gottlieb's e-book, "Living Up to the Truth".
Ultimately, no one can be sure that a given marriage or relationship will be successful so the benefits of any marriage must be considered at least a bit of a gamble. Furthermore, the cultural gap between a Jew and his non-Jewish partner is greater than in most marriages and that, both statistically and intuitively, can contribute to greater pressure and misunderstanding. Neither of those is healthy for a marriage. While, of course, any marriage can fail (in any number of ways) if the odds against a particular marriage are greater (as, statistically, mixed marriages involving Jews are far more often than not of shorter duration), that must count as a "cost" rather than a "benefit."
In addition, the human heart is a funny thing. I won't claim that this friend of yours is anything but the gracious, intelligent and decent person you no doubt consider her to be.
But I will suggest that, just as your heart was taken with her, it can as easily be taken with another. In other words: somewhere "out there" there's probably a Jewish girl who is as well or even better matched to you.
Torah literature actually supports that possibility as it teaches that God provides us with potential matches who - if we work hard at it - are eminently and absolutely suited to us. Not to mention that they're Jewish.
I don't know how helpful you will find all this. I've tried to present some pros and cons and I'll leave it to you do decide how to weigh the elements of each side.
A separate letter evoked a further discussion of consequences:
My question concerns the Law regarding marriage between a Jewish woman and a Christian, particularly as it relates to marriage ceremonies and the 'Jewishness' of the children. I am aware of course of the existence of matrilineal inheritance, but not the practical consequences for the children in an orthodox Jewish community
You are certainly correct to seek as much information as possible up-front, when change might still be an option. Jewish law does not regulate or recognize mixed marriages. "Kiddushin" the first legal step towards a Jewish marriage cannot be achieved between a Jew and a non-Jew. Even if a couple were to go through the various acts associated with marriage (chupa or the seven blessings for example) they would have no legal or religious effect.
Consequently, if the relationship were to come to an end, there would be no need for a Jewish bill of divorce (a get) because there was never a Jewish marriage to begin with.
As you already know, the children of this particular relationship would be considered completely Jewish and would be treated as such by the Jewish community. Since this has become something of a common occurrence in the modern world, much of the stigma once attached to children of mixed marriages is now gone and they could well travel freely through intensely Jewish lives unhampered by this part of their past.
The Jewish wife/mother, on the other hand, will likely find herself socially and religiously distanced from the core Jewish community. While she, too, is still Jewish, the act of intermarriage is still considered by many as an act of extreme disloyalty and rejection of the Torah.
Let me add a couple of observations of my own on the subject:
Let me first note that many Jews possess a very strong resistance to intermarriage - even Jews whose lives are lived in near-complete ignorance of the ideals of the Torah This resistance is borne of the (often subconscious) conviction that with an intermarriage, the Jewishness of that particular family has come to an end.
On a deeper level, though, I think it often comes from the subtle knowledge that in Jewish terms, the purpose of marriage has little or nothing to do with love and personal or mutual fulfillment (as important, desirable and reasonable as these things are). Rather, we primarily see marriage as a vital tool to be used in the task of creating and strengthening a society of thoughtful, moral and God-fearing citizens.
But for a family to teach (through lesson and example) the values needed for a proper Torah-oriented world, it must itself be firmly, intelligently and cooperatively committed to them. By the way, I think it goes without saying that a strong, loving and mutually supportive relationship between parents will go a long way to enhance the "delivery" of the message (not to mention providing many, many other benefits in all aspects of life)â€¦but it's still only a tool.
Now you can imagine how difficult it would be for a mixed marriage to fulfill these specifically Jewish goals. By laying the cornerstone of your family life on a foundation foreign to the lofty ideals and messages of the Torah, you are, in a way, banishing their happy and life-giving properties from your life!