To find out the answer, we have to go back to where it all started: Naomi's proposal to secure Ruth's future,
"Then Naomi her mother-in-law said to her, "My daughter, should I not seek rest for you, that it may be well with you? Is not Boaz our relative, with whose young women you were? See, he is winnowing barley tonight at the threshing floor.Frederic Bush commented that Naomi's suggestion for Ruth to wash, anoint and dress up is a symbolic gesture to start anew her life and move on; to end the mourning season for her deceased husband, Mahlon, as parallel David's ending his mourning for his dead son in 2 Samuel 12-14. (Frederic Bush, Ruth/Esther [USA: Word, 1996], p.152).
Wash therefore and anoint yourself, and put on your cloak and go down to the threshing floor, but do not make yourself known to the man until he has finished eating and drinking. But when he lies down, observe the place where he lies. Then go and uncover his feet and lie down, and he will tell you what to do." (v.1-4)
And that was exactly what Ruth did in the story. She moved on.
Next, this happened:
"So she went down to the threshing floor and did just as her mother-in-law had commanded her. And when Boaz had eaten and drunk, and his heart was merry, he went to lie down at the end of the heap of grain.Commentators agree that this account is sexually charged:
Then she came softly and uncovered his feet and lay down. At midnight the man was startled and turned over, and behold, a woman lay at his feet!
He said, "Who are you?"
And she answered, "I am Ruth, your servant. Spread your wings over your servant, for you are a kinsman-redeemer."
And he said, "May you be blessed by the LORD, my daughter. You have made this last kindness greater than the first in that you have not gone after young men, whether poor or rich. And now, my daughter, do not fear. I will do for you all that you ask, for all my fellow townsmen know that you are a worthy woman. And now it is true that I am a kinsman-redeemer. Yet there is a kinsman-redeemer nearer than I. Remain tonight, and in the morning, if he will redeem you, good; let him do it. But if he is not willing to redeem you, then, as the LORD lives, I will redeem you. Lie down until the morning." (v.6-13)
"That sexual overtones are present in the action of a woman uncovering a man's legs in the dark of the night and lying down, there can be no doubt."There is no question over the explicit sexual connotation in these passages. However that does not mean Ruth and Boaz had an intercourse.
(Frederic Bush, Ruth/Esther [USA: Word, 1996], p.153)
"The Narrator emphasizes the sexual nature of the midnight encounter by speaking only of "the man" and "a woman" without use of names (Ruth 3.8), evoking thoughts of the first pair in the Garden of Eden (Gen. 2.23)."
(E. John Hamlin, Surely There Is A Future: A Commentary on the Book of Ruth [USA: Wm. B. Eerdmans Publishing Company, 1996], p.43)
One ambiguity is whether did Ruth uncover Boaz's legs which includes his genitals? Frederic Bush thinks only the legs, not the genitals. Another commentator, Kirsten Nielsen, thinks that it was Ruth who undressed herself instead of she undressed Boaz. (Kirsten Nielsen, Ruth [UK: SCM Press, 1997], p.69-72) The debate is still unsettled though the philology makes more sense with Boaz being the one uncovered. What we are certain is that one of them was partial, if not fully, naked that night.
Some commentators say that there was no exposure of sexual organs in the story and Boaz did not have sex with Ruth because both of them were "worthy" individuals (Ruth 2.1, 3.11). The assumption is that having pre-marital sex in all circumstances is unworthy for "worthy" people.
I think to read certain moral code (i.e. pre-marital sex is unworthy) into the passages does not help us to understand the text simply because the text does not address the specific issue on the legitimacy of pre-marital sex. The question we bring to the text is not necessarily the question the text is meant to deal with.
My suggestion to understanding Ruth 3 is therefore to start with the main concern of the book: The theologico-political legitimacy of David, the southern king in the line of Judah, to be the ruler over all Israel. That means I think the canonical nature of the Book of Ruth lies in its function to legitimize the political authority of the southern kingdom over the northern kingdom. (Ruth 4.11-22)
The book of Ruth was designed to show us David's royal lineage. If lineage is the main theme, then the role of kinsman-redeemer in the story is the main feature as it ensures the continuity of the lineage (Ruth 4.5: "to perpetuate the name of the dead in his inheritance").
The author specifically mentioned the incestuous relationship between Tamar and her father-in-law, Judah, in 4.12 in tracing the lineage. This mentioning is carefully deliberated by the author in order to emphasize the significance of providing justice in the community as the sexual relationship with Judah was Tamar's demand of justice for herself when Judah deprived Tamar her lot when he did not give her his son, Shelah, as a kinman-redeemer as he has promised (Gen. 38.26).
(Strictly speaking, Judah's sexual relation with Tamar is not identical with the prohibition on incest stated in Leviticus 18.15. I am not aware of any law in the Old Testament that prohibit the widowed father-in-law from having sex with his widowed daughter-in-law for the sake of progeny. Neither there is a law that requires the father-in-law to carry out Levirate marriage. So technically, Judah's sexual relationship with Tamar is not under any incestuous category. In fact, there is no category for their act. There is a law on sexual relationship with a virgin woman [Deut. 22.28-29] but none on sexual relationship between widows. The statement "And Judah did not know Tamar again" [Gen. 38.26] seems to suggest that there was an expectation that Judah would continue to have sex with Tamar as if it was a norm in that culture for widowed father-in-law to have sex with his widowed daughter-in-law.)
Here we have an explicit and an implicit connections between the story of Boaz-Ruth and that of Judah-Tamar. The explicit connection is the theme on kinsman-redeemer to perpetuate the lineage of the deceased. The implicit connection that the author wants the readers to know is that Boaz was, like Judah, a widow.
Now, could the author of Ruth also raised up Judah's ignorance of his sexual encounter with Tamar as a parallel to tell the readers that Boaz was similarly ignorant of his sexual encounter with Ruth as he was drunk?
Did Ruth sleep with Boaz before marriage? We know that they did after marriage (Ruth 4.13).
Well, it seems to me that the low-self-esteemed statement made by Boaz "You have made this last kindness greater than the first in that you have not gone after young men, whether poor or rich" (Ruth 3.10) is his appreciative remark to Ruth for her choice to have sex with him rather than with others and for her desire to have him as the kinsman-redeemer. If this is the case, then 'first kindness' would be the reference to the sex they had when Boaz was unconscious, while the "last kindness" was referring to Ruth's invitation to Boaz to be her redeemer.
I do not claim this to be the case but that's the sense that I get from reading the passages. What about you?