The Book of Ruth is one of the most heartwarming stories of the Bible, a pastoral idyll with a happy ending, which is read every spring on Shavuot. A young widow with an uncertain future finds security with a well-off landowner, producing a son who will be the forebear of King David — and the dynasty of the Messiah.

But to read it as a 19th-century romance is to overlook more complex signals embedded in the text, according to Rabbi Deborah Kahn-Harris, who argues for a bolder alternative in her new book, Polyamory and Reading the Book of Ruth. The principal of London’s Progressive rabbinic training academy, Leo Baeck College, believes that rather than concluding with a portrait of simple heterosexual monogamy, it offers an example of loving and supportive polyamorous households, which she explains through analysis of the two triangular relationships in the story: between Naomi and her daughters-in-law Ruth and Orpah, and then Ruth, her husband Boaz and Naomi.

If this seems a little outre for conventional readers, then it’s worth remembering that for more than 2,000 years, rabbis have been amplifying, explicating and creatively reinterpreting biblical tales, unafraid to fill in what they have seen as narrative gaps. In the imaginative practice of midrash, they have often embellished stories in surprising ways.

“The classical rabbis…came to the text with their own experiences of life, their own cultural assumptions,” Kahn-Harris said. “It would be odd to think that they didn’t.

“Interpretation doesn’t stop. We are constantly doing it. All rabbis do it. We write sermons, we create homilies. We are doing something interpretative - even if we are doing that interpretation through the multi-layered conversation with the interpreters who have gone before us.”

Even in the most Orthodox circles, interpretation continues: “It’s just that it is more limited and constrained by the norms of that cultural space.”

When we read, all of us are influenced by the social mores and cultural preferences of our times. “There is no such thing as objective reading. We are all subjective, whether we are conscious of our subjectivity or not,” she said.

Her own reading slowly took shape in the course of many years of teaching the megillot to students, where she has deployed insights not only from rabbinic midrash but more contemporary academic approaches including those from feminist and queer studies. Citing the work of other scholars, she notes “a well-established tradition of lesbians seeing themselves in the Naomi-Ruth relationship”.

“When we think of mothers-in-law and daughters-in-law, we might think of a quite wide generational gap. But in antiquity that may well not have been the case.” It is “very plausible there is 15 to 20 year age gap between them”.

She emphasises that she “always tries to root what I am doing in the language, in a close reading”. But if the text does not support it, “for me personally as a rabbi, as a Bible scholar, I would shift that reading to one side and say that is not something I can make an argument for.”

She scrutinises particular words such as the word “cling” when Ruth is said to “cling” to Naomi. Or chesed — lovingkindness, but capable of multiple meanings — which binds the relationships together. Ruth is the only biblical book when the Hebrew verb to love, ahav, is used of two women — though she adds that it may indicate various kinds of love and not simply erotic.

Rabbi Dr Deborah Kahn-Harris

Teasing out the meaning involves not only examining what is said but what is not, or what is not said explicitly. Ruth contains more dialogue than any other biblical book. In listening how the characters express themselves or respond to others, the attentive reader can discover hints and nuances that may not be obvious from a superficial reading.

Biblical narratives are often “notoriously terse”, hence the midrashic impulse to read between the lines. There is no backstory for Boaz, one of the central characters, for instance, so “we have to create our own backstory”. Unusually for a biblical hero, he is unmarried when he appears (although one midrashist, obviously a little troubled by this, makes him a widower). What’s more, Kahn-Harris said, “He doesn’t seem to have the idea that he needs to be married. Even when Ruth goes down to the threshing room floor, there is this wonderful verse where it says he was startled. ‘And behold, there was a woman lying at his feet…’ as though this was a surprising thing to have happened to him.”

Polyamory is “not strange” to the Bible, she observes, but it in the context of patriarchal polygamy - and such households are not often happy places. Think of the tension between Hagar and Sarah or the rivalry between Rachel and Leah.

While her study is academic, with plentiful footnotes and the occasional terms like “dyadic” (referring to a relationship of two, rather than more partners), she hopes it will have an influence beyond academia. It is important for those in polyamorous families or LGBT people to see themselves reflected within the stories of the Bible, she believes.

The book ends with her adaptation of another rabbinic form, Targum, in which translators not only translated from the original Hebrew but added glosses to explain the text. Her own version of Ruth here and there includes additional phrases that bring out what she believes is the latent meaning.

Texts are “pregnant with potential meaning,” she said. “I am not trying to say my reading is the most correct, the only reading… it is in addition to all these other readings. It becomes another possible reading…

“Unlike virtually every other case of patriarchal polygamy practised in the Bible - which is dysfunctional in terms of the interpersonal relationships - I am making a case for a multi-person household which is mutually supporting and caring and loving. That is what I am saying polyamory is and that is why I am using this term which didn’t exist in biblical times.

“But because a piece of language doesn’t exist doesn’t mean that concepts, that emotions haven’t existed for several millennia. And to assume that our biblical ancestors didn’t understand the full range of human emotions is a greater disservice to our tradition… than to say this is woke academia.”

Polyamory and Reading the Book of Ruth is available from Lexington Books at £73. Deborah Kahn-Harris will be speaking about it at Book Week at 2pm on Sunday, March 10, details from jewishliteraryfoundation.co.uk