Is Common-Law Marriage Binding?

Can we rely on Rav Yosef Eliyahu Henkin psak halakha in Perushei Ibra, Chapters 3-5. Rav Henkin argues that a couple need not intend to marry according to Jewish law for kiddushin to take effect. His psak halakha considers kiddushin to be created when a couple engages in marital relations and intends to have a permanent monogamous relationship? If so, does the Hilchos of Yichud apply in the above jewish relationship according to if a jewish couple is frum and living together as man and wife for 8 years?

Shalom!

Thank you for your question.

You are correct that Rav Yosef Eliyahu Henkin argued that if a couple intends to be married and committed to each other, then their marital relations constitute their “Kiddushin” – halachic marriage. He was of the opinion that halachic marriage takes effect even if the couple does not intend to marry according to Jewish law.

Nevertheless, as great as Rabbi Henkin was, the overwhelming majority of halachic authorities have rejected Rav Henkin's opinion. Indeed, the Shulchan Aruch and Rema all oppose Rav Henkin’s opinion and rule that a couple is not halachically married if the man and woman do not intend to marry according to Torah law. It goes without saying that "Yichud" is forbidden.

However, even a couple who was only married by common-law should still go through with a Jewish divorce, a "Get," in the event that they decide to part ways. 

1. Gittin 81a; Rambam, Hilchot Ishut 7:23.