I'm not aware of any Jewish law that said Gentiles can't fellowship with Jews. Gentiles weren't under Jewish law ... that's why they're called Gentiles.
Btw, it's my understanding that the Jewish "law" to not socialize with Gentiles is not part of law of Moses. It was a man-made custom, designed to keep Jews getting involved in pagan practices, like consuming non-kosha food. No need for Christians to follow man-made laws.
What you said in your post is not correct. Jews and Gentiles cannot associate with one another, marry, and never eat together. The Gentiles are unclean, uncircumcised, filthy sinners, dogs.
Acts 10:28-29
And he said to them, “You yourselves know that it is forbidden for a Jewish man to associate with or visit a foreigner; and yet God has shown me that I am not to call any person unholy or unclean. That is why I came without even raising any objection when I was sent for.”
Isaiah 52:1
Awake, awake, Clothe yourself in your strength, Zion; Clothe yourself with your beautiful garments, Jerusalem, the holy city;
For the uncircumcised and the unclean (Gentiles) Will no longer come into you.
Ezekiel 44:7
When you brought
in foreigners, uncircumcised in heart and uncircumcised in flesh, to be in My sanctuary to profane it.
Ezekiel 44:9
‘This is what the Lord God says: “
No foreigner uncircumcised in heart and uncircumcised in flesh, of all the foreigners who are among the sons of Israel, shall enter My sanctuary.'
Ezra 9:11-12
Which thou hast commanded by thy servants the prophets, saying, The land, unto which ye go to possess it,
is an unclean land with the filthiness of the people of the lands, with their abominations, which have filled it from one end to another with their uncleanness. Now therefore give not your daughters unto their sons, neither take their daughters unto your sons, nor seek their peace or their wealth for ever: that ye may be strong, and eat the good of the land, and leave it for an inheritance to your children for ever.
Matthew 15:22-28
And a Canaanite woman from that region came out and began to cry out, saying, “Have mercy on me, Lord, Son of David; my daughter is severely demon-possessed.”
But He did not answer her with even a word. And His disciples came up and urged Him, saying, “Send her away, because she keeps shouting at us!” But He answered and said, “
I was sent only to the lost sheep of the house of Israel.” But she came and began to bow down before Him, saying, “Lord, help me!”
Yet He answered and said, “It is not good to take the children’s bread and throw it to the dogs.” And she said, “Yes, Lord; but please help, for even the dogs feed on the crumbs that fall from their masters’ table.” Then Jesus said to her, “O woman, your faith is great; it shall be done for you as you desire.” And her daughter was healed at once.
Ephesians 2:11-12
Therefore remember that previously you, the Gentiles in the flesh, who are called “Uncircumcision” by the so-called “Circumcision” which is performed in the flesh by human hands,
remember that you were at that time separate from Christ, excluded from the people of Israel, and strangers to the covenants of the promise, having no hope and without God in the world.
Ephesians 2:14-15
For He Himself is our peace, who made both groups into one and broke down the barrier of the dividing wall,
by abolishing in His flesh the hostility, which is the Law composed of commandments expressed in ordinances, so that in Himself He might make the two one new person, in this way establishing peace.
The Jews were disgusted at how the Gentiles behaved, what they ate, they were uncircumcised, they were unchosen. The Gentiles were filthy sinners and were prohibited from entering the temple in Jerusalem. The Jews saw the Gentiles as dogs.