It is bride singular in the Greek, never brides plural because there is one symbolic bride not two.
Technically there are two, but Jacob is the first, not the church. Jesus spends the Day of the Lord, the Millennium with Israel. The church is still waiting in Paradise, like Jacob has had to wait during the fulness of the Gentiles. The wedding of Israel was supposed to happen in the first century, but the redemption of mankind was not complete, and has been ongoing for the last 2 millennia.
Amil will state that Revelation 19 and 21 are the same event.
"Let us be glad and rejoice, and give honour to him: for the marriage of the Lamb is come, and his wife hath made herself ready. And to her was granted that she should be arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints."
The first marriage down the isle, so to speak, from heaven to earth are those armies on white horses. That is not the church bride. The church bride comes down in the New Jerusalem after the Day of the Lord.
The church is not married twice. One bride comes on white horses. The other in the New Jerusalem. Unless you follow Amil theology, there are two brides. Reformed amil will tell you the church is the only Israel bride. Historist do not allow such a distinction between two brides either as they lean towards post mill as only a single bride as well.
The majority of the church today is unwilling to see that at the 6th Seal, the church is removed, and then Jacob is placed front and center. That is even what Paul wrote:
"For I would not, brethren, that ye should be ignorant of this
mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: For this is my covenant unto them, when I shall take away their sins."
Obviously for most it is still a mystery to them, that is resolved at the 7th Trumpet:
"But in the days of the voice of the seventh angel, when he shall begin to sound, the
mystery of God should be finished, as he hath declared to his servants the prophets."
The Millennium is the promised marriage life as expressed here:
"Seventy weeks are determined upon thy people and upon thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy."
That is the promised relationship of the metaphor husband and wife promised by God. That will be life in the Day of the Lord without sin and natural decay from the bondage of sin. That is the promise of Isaiah 65. That happens pre-mill not after Revelation 20.