OK, there's one book, which I've been recommending ever since I read it [yes, that's right I have read at least one book whilst on my degree course!]: The Five Love Languages [Gary Chapman]
Although it is actually written in the context of a married relationship, there are in fact many principles which can be applied to other contexts [i.e. single, those in a relationship or a courtship or even engaged]. However, what has been an intersting reflection [i.e. Wednesday] is how this could affect my perception of God's love. Another reflection is from my reflecting his theory that there are 5 separated 'languages' that people communicate love [Acts of Service, Gifts, Quality Time, Words of Affirmation, & Physical Touch], then thinking about if one [or more] of those is removed - one can feel so negative towards someone who is not 'showing love'.
Intersting reflections & it's definitely worth a read - it's made a difference to my own approach towards love - how I perceive it, as well as how I show it.