You said that books can not make a person mature - that is correct - a person has to WANT to mature in order for anything to work!
But what some of these books CAN do (and this is why I like the Cloud/Townsend books over some others out there) is provide practical ways on applying the Bible to our lives, especially in regards to relationships, and how to protect ourselves from making dangerous decisions relationship-wise.
Some people, myself included, find that the Bible is not specific on certain issues, and we can get a general gist on how to handle ourselves, but sometimes need some nitty gritty graphic detail to learn how to separate the 'chaff' that we learn each day from the 'wheat'.
That's why I started this thread, and I'm hoping it can stay on-topic. A lot of us read good relational books, and a lot of us are searching for good books to help us understand what it is God requires from each of us - take a look around your local Christian bookstore - whenever I go to mine, most adults are congregated around the relationship area of the store!
I thought this could be a good thread for us to share which books have been instrumental to us becoming healthy relating adults. Some people might think that these books are a waste of time, and choose to read nothing but the Bible about this issue. That's fine for them, and it's not what this thread was about. If you feel that way, well you don't need to read this thread then!

However, if you do desire to read some good books on being a healthy individual in a relationship, and developing a healthy relationship (or are looking for good books to give to young people in your congregation/family) within the Biblical framework, than you'd do worse than to look at this thread!
Cherub, I would recommend you have a read of Boundaries though. A lot of Christians have issues with the word 'boundaries', as we're continually told to open our hearts, serve continually, bless each other, etc etc. Sometimes, however this 'serving' gets into unhealthy areas (often ones of co-dependance, an inability to say no to people, a lack of time for family, etc etc), and that's why I believe this Boundaries series is one of the most important ones to hit Christian bookstores.
Anyway - back to the topic. If you were to recommend a good book for young people or ANY person wanting to develop a healthy relationship - what books would you recommend?
Sasch
ps. Other books from Cloud/Townsend include Boundaries, Boundaries in Marriage, Boundaries with Kids, Boundaries Face to Face, Safe People, Who's Pushing Your Buttons, God Will Make A Way, How People Grow, Changes That Heal, The Mom Factor, Hiding From Love and 12 "Christian" beliefs that can drive you crazy. Alternatively check out
www.cloudtownsend.com