This is a pretty straight forward recommendation of a book that will greatly help your relationship! If you're single, this will help in preparing you to love another and if your in a relationship, it will greatly help you in showing your love!
The Five Love Languages by Gary Chapman helps to discover your own love language and to discern that of others.
The Five Love Languages are;
Words of Affirmation
Quality Time
Receiving Gifts
Acts of Service
Physical Touch
Also - take the 30 second assessment for an indication of your love language.
For further Ideas see here and here