That's a little difficult since codependency happens within the context of a relationship. I can give three recommendations that do not specifically focus on romantic attachments, but all the books I know of at least touch on the subject since it is the primary intimate relationship in adults' lives.
Here are the books:
The Dance of Intimacy: A Woman's Guide to Courageous Acts of Change in Key Relationships by Harriet Lerner, PhD
Codependent No More by Melodie Beattie
Boundaries: When to Say Yes, How to Say No to Take Control of Your Life by Drs. Henry Cloud and John Townsend
Me: BW, 40.......Him: FWH, 40
Not all of these use the term "codependent" but they all get at the types of behaviors and thought patterns that characterize codependence.
DS1: 11, DS2: crawling
Status: R going well
"When you can tell the story and it doesn't bring up any pain, you know it is healed." - Iyanla Vanzant, Broken Pieces