What is the meaning of the quote Love will not serve those who do not live for her and in her and to whom she is not the breath of life?

This means that if love is not (very) important to you, you will not do well in love. That is you must care very much for love (nurture love, appreciate those you love) in order to be well served by it. In other Words to do well with relationships, you must put in effort, energy and care.