Re: Could the Woman At The Well be in concubine relationship
Regarding Ruth, I think that technically the Levirate marriage would have been offered to Naomi (assuming Boaz was her husband's brother or close relative). But being too old to have children, Ruth received the Levirate marriage as a substitute. The fact that it doesn't strictly follow the law regarding Levirate marriage is interesting, either the culture as a whole or Boaz personally extended it through generosity. But that's off-topic.
This idea also doesn't work because:
Abishag, the virgin David took in his old age, is called his "concubine". If virgins were always "wives", she would have been called a wife.
Now, he didn't actually have sex with her, so there was no blood covenant - but if consummation forms the marriage, without sex she wouldn't have been his concubine either. The fact she is called his concubine shows that it is the covenant that makes the marriage, not the sex - but that's a topic that's been thrashed out elsewhere!
I have always also assumed that the handmaids of Sarah, Rachel, Leah etc were young girls who were servants of their mistresses, and then once of age were offered to their mistresses husbands as concubines. So they too would have been virgins. This isn't overtly stated. But it would be hard to imagine them all being non-virgins.
Solomon had 300 wives and 700 concubines. Did Solomon, the wealthiest king ever, decide to marry 700 non-virgins, when he had access to any virgin he desired?
The idea that a concubine is a wife with an agreement that has different inheritance rights in it has scriptural support. The idea that it is the lack of a blood covenant is, in my opinion, wild speculation that just doesn't make sense in too many scriptural examples.