Scripture (Rev 19:7, 9) often refers to marriage, the meaning God gave to it, and its renewal in the covenant made by Jesus with his Church. Through marriage, the couple witnesses Christ's spousal love for the Church. The Sacrament of Marriage is a covenant, which is more than a contract. Covenant always expresses a relationship between persons. The marriage covenant refers to the relationship between the couple, a permanent union of persons capable of knowing and loving each other and God. The celebration of marriage is also a liturgical act, appropriately held in a public liturgy at church. You may find virtual 7 day marriage retreat here and catechesis on the sacrament of matrimony here.