I think conversion would be expected, and it wouldn't be thought of as "forcing." It would just be expected. By the time any girlfriend or boyfriend would come to the point, cross that bridge so to speak, he or she would understand full well that this is a religious family and there are certain expectations. I mean, if you're dating the son of a Rabbi, at some point you have to ask yourself, would I be willing to convert to Judaism for this person? If you're not, figure that out sooner rather than later, I hope!