A useful little book from 1996 discussing the human hunger for intimacy and how it can be experienced with yourself, others and God, written by New Zealand national treasures John and Agnes Sturt. Some excellent insights, with a research aspect, a lot of practical material, a few tasty quotes and a couple of classic simplistic Christian cliches (eg, 'the Bible is God's love letter to mankind' and 'you can be as close to God as you want to be (if God feels distant, guess who moved etc)' or words to that effect).
Full of good advice and principles for building an intimate relationship - whether it be a romantic relationship or not. I would recommend working through the exercises at the end of each chapter together with someone close or in a group to get the most out of the book.