Jacob calling Rachel his wife prior to the wedding followed common practice – a betrothed woman had the status of a wife (Deut. 20:7; 22:23-24). The Mesopotamian Code of Hammurabi attests to this custom in laws 130 and 161.ESV Archaeology Study Bible, p. 52
I took note of this information on Genesis 29:21 because this custom is still carried out among our focus people group. Early on, I ended up in thoroughly confusing English conversations with local friends after they told me they now had a wife. I would respond with hearty congratulations and ask them when the wedding had taken place. When they would respond in the negative, that the wedding had not yet taken place, I would insist that they must have meant they had a fiance, not a wife. But they would insist that no, they meant wife.
Clarity eventually came when we realized that the local language often refers to a woman as a wife from the moment of engagement. Even though they are not living together and there hasn’t been a wedding, she is still considered officially the wife of her betrothed. My local friends were carrying this aspect of their language into English, much to my confusion. Turns out our sequential understanding of male-female romantic relationships in the West is quite different from how these things are spoken of in Central Asia. But their way of doing things probably has stronger precedent than ours, going all the way back to the time of the patriarchs and even Hammurabi!
Another linguistic surprise was how families would speak of brides. An elderly man once told me that he had four brides, one of them new. But it wasn’t polygymy that was going on. Sometimes that does happen among our people group, leading to this very un-Islamic but honest experience-based proverb: A man with two wives is a man with a liver full of holes (i.e. he leads a painful life). However, in this situation, this man’s son had just gotten married. In the communal (rather than individualistic) thinking of this man, the brides who married his sons were obviously the family’s brides. He could even accurately say they were his brides. The mother-in-law could say this also. It is said in the West that you don’t just marry an individual, you also marry their family. Well, in the Middle East and Central Asia, that concept has been taken to a whole new level and is communicated even by the languages themselves as they speak about who the brides belong to.
After a successful proposal, a man in the West might say, “This is my fiance and my future bride.” In Central Asia, during the same stage you’re just as likely to hear him say, “This is my wife and our bride. Want to come to the wedding in six months?”