Read verse 13. The sex didn’t take place on the threshing floor, as much fun as that story is. It took place in verse 13.Go read the story again... It was a legally handled case.
Rth 4:8 Therefore the kinsman said unto Boaz, Buy it for thee. So he drew off his shoe.
Rth 4:9 And Boaz said unto the elders, and unto all the people, Ye are witnesses this day, that I have bought all that was Elimelech's, and all that was Chilion's and Mahlon's, of the hand of Naomi.
Rth 4:10 Moreover Ruth the Moabitess, the wife of Mahlon, have I purchased to be my wife, to raise up the name of the dead upon his inheritance, that the name of the dead be not cut off from among his brethren, and from the gate of his place: ye are witnesses this day.
Rth 4:11 And all the people that were in the gate, and the elders, said, We are witnesses. The LORD make the woman that is come into thine house like Rachel and like Leah, which two did build the house of Israel: and do thou worthily in Ephratah, and be famous in Bethlehem:
They were not joined together yet because Boaz knew that there was another man "closer" to Ruth than he was. So, it was made legal in chapter 4 before they were "joined together"/Married!
13 ¶ So Boaz took Ruth, and she became his wife, and he went in to her. And the LORD fnenabled her to conceive, and she gave birth to a son.
Boas took Ruth and she became his wife. All of that stuff with the shoes was just details. Unless you think we should still be exchanging shoes and that all weddings should accompany real estate inheritances the this isn’t a norm setting event. There are no norm forming events.