We have a custom to recite Shir Hashirim (The Song of Songs) on the Shabbat during Pesach. Many reasons have been offered to explain why. One is that Pesach  takes place in the month of spring (Chodesh Haaviv), and Shir Hashirim is a song about spring and renewal. “Behold the winter has passed; the rains are over and gone; the blossoms have appeared in the land, and the time of pruning has come”(Song of Songs:Ch. 2:v.11-12).
 
It is most probable, however, that the reason for reading Shir Hashirim on Pesach is actually to be found not so much in the text of the Song, in its simple meaning, but rather in its Midrashic meaning. Rabbi Akiva was the most outspoken advocate of the view that Shir Hashirim (The Song of Songs) is actually a parable of the passionate love between G-d, the Lover, and Israel, the beloved. As Rabbi Akiva said, “All of creation does not compare in worth to the day when Shir Hashirim was given to Israel. For all of Tanach is holy, but Shir Hashirim is the holiest of the holy.”(Mishnah Yadayim:3:5).
 
The specific connection to Pesach is the fact that this interpretation sees in Shir Hashirim a depiction of G-d coming to redeem Israel from slavery, not only in the past in Egypt, but also in the future redemption yet to come. For example the verse, “With me from Lebanon, with me from Lebanon – come!” (Shir Hashirim:4:8) is read as if it is said not “from Levanon” but “from levaynim” – bricks. “While you were still working with mud and bricks [i.e. – enslaved in Egypt], I, the Holy One Blessed Be He, jumped in and redeemed you.” (Midrash Shir Hashirim:4:17).
 
Similarly in verse 2:8 “Hark! My beloved! There he comes…” is interpreted both as referring to Moshe telling the enslaved Jews that G-d will come to redeem them soon and also to the Moshiach, who will announce the future redemption at Pesach time (Midrash Shir Hashirim:2:19). Thus reading Shir Hashirim on the Festival of Redemption, the time when the coming redemption is also to take place according to the Midrash makes perfect sense.
 
Regarding the Midrashic interpretation of Shir Hashirim, Rabbi Akiva saw the passionate love relationship of man and woman as the best and highest expression of the love that should exist between G-d and Israel. The Torah itself as well as the prophets utilize the language of love, fidelity, infidelity and marriage in regard to G-d and Israel. The Rambam states in Hilchot Teshuva (Chapter 10), that a Jew’s highest purpose & goal in life is to be madly in love with the One Above.   
 
Therefore, the first Mitzvah of the Torah is to marry and raise a family. The Zohar explains that the passionate love between husband and wife teaches us how to love G-d. Thus, according to the Zohar, in order to love G-d properly and fully, a person must first experience passionate love for his or her spouse.