A new alternative has come up to temporary "misyar" marriages, and this one is approved by Saudi authorities.
Called "Daytime Marriage," this allows a man to have two wives - one for the day shift and one for nighttime.
The advantages are said to be that with this sort of marriage, women who work at night can also enjoy the benefits of marriage. Or, at least, some of them.
Apparently, some older women are taking advantage of this arrangement, marrying younger men as second wives. Many of them are divorced or widowed, making them less than ideal for first marriages.
Men who are taking advantage of this system are being careful to hide the "daytime wives" from their first wives.
Unlike misyar marriages, these are meant to be permanent.
Saudi religious scholars are lauding the advantages of this system. It reduces promiscuity for women, especially night workers; plus it helps stem divorces for men who need more action (and who manage to hide their daytime wives from their first wives.)
I think that the English word for these women is "mistresses."