Can a Noachide have pre-marital sex if he stipulates that the relationship is permanent until a given condition?

Question

According to this (https://asknoah.org/forum/showthread.php?tid=2027), Noachides are not permitted to have premarital hookups. Sex is permitted in a permanent/long-term relationship, which is considered equivalent to marriage. But is there a minimum length of time for such an arrangement? Can a person engage in relations if she stipulates that the relationship will last for a week, or until both parties decide to move on, and so forth.

Answer 1

I know of no Halachic problem with a Noahide having premarital hookups with non-Jewish women; including “one-night stands”.

The thesis posited in the linked article; that for Gentile men, having sex without the bond of marriage “is deemed to be immoral and disdainful in G-d's eyes”, is not supported by any Halachic sources.

The article later appears to backtrack a bit, and states, “Although such relations are not clearly forbidden for Gentiles, it is a repulsive act, even if done in a temporary fashion.” This is an admission, that the author has no clear Torah source that forbids gentiles from engaging in such relations. Additionally, his pejorative assertion, that even for Gentiles, it is a repulsive act; is likewise not sourced in Halacha.

Non-Jews do not necessarily need to be married, in order to be allowed to engage in sexual intercourse. See Maimonides (Yad, Ishus 1:4) regarding harlotry between Noahides, and there is no apparent moral fault in a non-Jew paying a sex worker for her services.

Also in his Guide to the Perplexed (3:49) he says that prior to Sinai, having relations with a sex worker was a permissible act, on equal moral footing of an Israelite, post-Sinai, having relations with his wife.

Maimonides (ibid.) refers to the story of Judah and Tamar (Genesis 38), and explains that the “shame” mentioned there (v. 23) merely refers to the fact that even in their society, matters of sexuality were best left un-discussed. Judah was also concerned that he would loyally fulfill his contractual obligation of paying the harlot for her services, and neglect to do so would constitute a form of theft.

While non-Jews are not necessarily considered to be married, even if they engage in sexual intercourse, however if a Noahide is interested in having a longer-term relationship, then that might be considered the Noahide equivalent of “marriage”. That will have Halachic implications, in that the woman can’t have any relations with other men during this time period, as long as she’s considered married to her current sexual partner. The time period of Noahide “marriage”, is until one of the parties decides dissolve their relationship [see Maimonides (Yad, Melachim 9:8)].

Answer 2

Pre-marital sex often leads to wasting of the seed/semen, which is a grave sin punishable by death, per Bereishit/Genesis chapter 38, verses 8-10:

"So Judah said to Onan, "Come to your brother's wife and perform the rite of the levirate, and raise up progeny for your brother."

Now Onan knew that the progeny would not be his, and it came about, when he came to his brother's wife, he wasted [his semen] on the ground, in order not to give seed to his brother.

Now what he did was evil in the eyes of the L-rd, and He put him to death also."

By the way, in the same chapter, we find out that Onan was also a gentile, the product of Judah's union with a Caananite woman, Shua.

Trust that Hashem will lead you to the right woman instead of sleeping around.