Have a look at the Netherlands where this is allowed 23 years:
20 years of gay marriage in the Netherlands: 20 thousand couples | CBS
"Marriages between two women are of a shorter duration than marriages between two men or between a man and a woman. Of the women who married another woman in 2010, 26 percent were divorced after almost ten years (on 1 January 2020). This is almost twice as much as for married male couples (14 percent). The divorce rate among heterosexual couples is comparable to that of gay male couples: 16 percent were divorced after ten years."
CBS = Central Buro of Statistics in the Netherlands, so a reliable source.