We're smack-dab in the middle of a series at Element called "Rated R: Relationships, Sex, and Spirituality," and I've taken the opportunity a couple of times to recommend some related books to our folks. I figure I can mention them here, as well, since, if you're like me (a reader and someone in a relationship), you're always up for book recommendations. They aren't very obscure titles, but maybe one or two of these will be new to you.
This list is sort of what I'd come up with if someone asked me to make a required "Men, Women, and Marriage" reading list.
Sacred Marriage by Gary Thomas*
For Women Only: What You Need to Know About the Inner Lives of Men by Shaunti Feldahn
For Men Only: A Straightforward Guide to the Inner Lives of Women by Shaunti Feldahn and Jeff Feldahn
Point Man: How a Man Can Lead His Family by Steve Farrar
Love and Respect by Emmerson Eggerichs
Sex and the Supremacy of Christ edited by John Piper and Justin Taylor
And then I might throw in As For Me and My House by Walter Wangerin, The Act of Marriage by Tim LaHaye, Sex Begins in the Kitchen by Kevin Leman, and a very qualified recommendation for His Needs, Her Needs by Willard Harley.
* This is the absolute best marriage box I've read (and I've read quite a few). Generally speaking, Gary Thomas is one of Christian publishing's best kept secrets. It's a shame how unfamiliar Christian readers are with his writings. If you like the Christian Living genre but are burned out on the crap that passes for it, reading Thomas is very, very necessary.