Kaveh is the crown prince of The City of Red Clay and the on-paper husband/beard of Queen Shulamit, ruler of the neighboring kingdom of Perach, in Shira Glassman's Mangoverse book series.
Being the son of an overbearing bully is bad enough under ordinary circumstances, but infinitely worse when he is also the king. When his father has Kaveh’s boyfriend Farzin arrested for leading a worker's strike, Kaveh goes to the neighboring kingdom of Perach and its lesbian Queen Shulamit, hoping that some LGBT solidarity will persuade her to help rescue his lover. The two of them make a deal: she'll aid him in freeing Farzin and hopefully find a way to calm his father down in the process, and he'll become the official prince consort of Perach.
Obviously, it's intended as a sham marriage as the two monarchs are both deeply in love and monogamously committed to other people, but they're also both in need of legal heirs — and bringing home a wife would go a long way to persuading Kaveh's homophobic father to leave his boyfriend alone. Thanks to the intervention of Shulamit's court wizard, the two of them are able to produce an heir without having to consummate their marriage, and they remain good friends and co-parents for the rest of the series.
Kaveh is a sweet but nervous man who initially has trouble managing his emotions. However, thanks in part to Aviva, Shulamit's actual consort, he learns healthier coping mechanisms and becomes a happier person as a result. Unlike Shulamit, Kaveh is bisexual, but his commitment to Farzin puts any other kind of marriage completely off the table, as he's unwilling to cheat on his partner or trap a woman in a loveless marriage.