You may recall that Hosea is the prophet whom God told to marry a prostitute woman named Gomer, who was as repeatedly unfaithful to him as Israel was repeatedly unfaithful to God (by idolatry, breaking the Covenant, etc.). The point was to show Israel that God would still love Israel and stay married to her, although He also expected Israel to quit pulling this junk. Also, it showed that Israel getting picked by God to be His chosen people was like Gomer being picked by Hosea out of prostitution to become his wife.
So Gomer, who was unloved, became Hosea’s beloved and wife.
And both Israel and the Gentiles, who were unloved, became God’s beloved people and His Bride.
Covenants are all about marriage or adopting kids, or making peace between tribes and cities and countries using the language of marriage and adoption. So nuptial imagery is very common.