This is a great question. There were many reasons for the writing of this treaty on love. In view of this let me give you a few reasons.
First, during Bernard's time many people were writing on this topic of love. For example, Peter Abelard wrote on this topic. More specifically, it was on the topic of the atonement, which connected to the topic of love.
Second, Bernard was an abbot. So, one of his main points was to write on the love of God. Moreover, he thought God was worthy of this love, that is, the love of all people. In light of this, he wanted to write something to help people love God more. You can tell from the headings that it was to instruct people. Let me give you some of the heading of the work:
- Why Should God be loved?
- The first degree of Love: Love of self for self's sake.
- The second degree of love: Love of God for self's sake; The third degree: Love of God for God's sake,
- The fourth degree of love: Love of self for God's sake
- Of the attainment of this perfection of love only at the resurrection
As you can see, he mainly wrote this to help people.