I would first like to offer one passage in the New Testament that effectively answers both the issue of intermarriage between Israel and Gentiles, as well as the state of the Torah of Moshe.
In Ephesians 2:14-16, the apostle Paulos wrote,
14 For he is our peace, who made both, one, and destroyed the middle-wall of the fence, 15 when he abolished the enmity by his flesh, the Law of commandments in decrees, in order to create in himself one new man of the two, making peace, 16 and in order to reconcile both to God in one body, by means of the cross, when he slayed the enmity on it.
In the Epistle of Aristeas, §§139-143, it is written,
Now our Lawgiver being a wise man and specially endowed by God to understand all things, took a comprehensive view of each particular detail, and fenced us round [περιφράσσειν] with impregnable ramparts and walls of iron, that we might not mingle at all with any of the other nations, but remain pure in body and soul, free from all vain imaginations, worshiping the one Almighty God above the whole creation. Hence the leading Egyptian priests having looked carefully into many matters, and being cognizant with (our) affairs, call us "men of God." This is a title which does not belong to the rest of mankind but only to those who worship the true God.
The rest are men not of God but of meats and drinks and clothing. For their whole disposition leads them to find solace in these things. Among our people such things are reckoned of no account. but throughout their whole life their main consideration is the sovereignty of God. Therefore lest we should be corrupted by any abomination, or our lives be perverted by evil communications, he hedged us round [περιφράσσειν] on all sides by rules of purity, affecting alike what we eat, or drink, or touch, or hear, or see.
English translation according to R.H. Charles.
According to Aristeas, Moshe "fenced" the Israelites with the Torah in order to prevent inter-marriage and a variety of other acts. The verb translated as "fence" is περιφράσσειν, which is related to the noun φραγμός in Eph. 2:14.
The apostle Paulos states that Christ destroyed the Torah by his death on the cross. Likewise, by destroying the Torah, he united both Jews and Gentiles into one new man in his body, the body of Christ.
The body of Christ is known as "the Israel of God" (Gal. 6:16), for the apostle Paulos states (Rom. 9:6-7), "Not all those who are of Israel are 'Israel,' nor because they are the seed of Abraham, are they all children, but 'In Isaac shall your seed be called.'"
While unbelieving Jews, i.e. the seed of Avraham according to the flesh (Rom. 4:1), are "Israel according to the flesh" (1 Cor. 10:18), they are not the promised seed, the Israel of God, i.e. Israel according to the spirit. Rather, only those who believe in Christ, and are thus "in Christ," comprise the Israel of God.
the Torah of Moshe was destroyed on the cross, along with the enmity it produced between Jews and Gentiles. Therefore, the restriction on intermarriage is void.
Believing Jews and Gentiles become one new man in the body of Christ.
There is neither Jew nor Greek in Christ, according to the spirit.
Israel is indeed the bride in the Old Testament, and Israel (the Israel of God), i.e. the Church, remains the bride in the New Testament. As for New Jerusalem, a case can be made that it is a metaphor for the Church. I believe Soldarnal made a recent thread about John 14 where Jesus says, "I go to prepare a place for you." I can't find the thread though.