There are three expressions for the word love in the Greek language: "eros" means the legitimate, sexual love, "philadelphia" is equal to sympathy and means love for friends and relatives, "agape" from the Greek New Testament stands for God's love in Jesus for us and means the love that serves others, such as our neighbours.
In the Old Testament, in 1st Mose 2,18-24, we've already learned about the development of love. In order that a man shall not remain lonely God gives him a woman-partner with equal rights to create a long-term relationship between man and woman.
Love between man and woman is praised in the Old Testament. In the Song of Songs, the most beautiful song by King Solomon legitimate love is glorified. It was interpreted as a metaphor for the love of God for his people Israel, and later seen as the connection of Christ with the church.
Paul speaks about love in the New Testament, in 1st Corinthians, 13 . You can recognise the nature and Being of Jesus if the word "love" is replaced by the name "Jesus". This means not only is it for oneself, (not the "I/me"), but the love for others/neighbours, (the "you"). Paul speaks about the unsurpassed love of God in Jesus for human beings. This love is called agape which Christians pass on.
This kind of love also stands for the ideal situation of love between man and woman.