I was curious as to why J. Gresham Machen never married. Apparently, he came close, but the woman was a unitarian, so the relationship never moved beyond a romantic attraction. See more here, at Triablogue.
Why Did Machen Never Marry?
Published
The Machen Seminar 
What Machen seemed to find in Herrmann was what he had apparently not found either in his home or at Princeton, namely, passion and joy and exuberant trust in Christ. At Princeton he had found solid learning and civil, formal, careful, aristocratic presentations of a fairly cool Christianity. He eventually came to see that the truth of the Princeton theology was a firmer ground for life and joy. But at this stage, the spirit in which it came, compared to Herrmann’s spirit, almost cost evangelicalism one of its greatest defenders. There is a great lesson here for teachers and preachers: that to hold young minds there should be both intellectual credibility