I didn't know of Max of Baden.
Ernie of Hesse, twice married with children by either wife.
Aribert von Anhalt, the estranged husband of Pss Marie Louise of S.Holstein.
GDk Serge of Russia, married to Elisabeth of H.Darmstadt.
Pr.Pierre of Polignac, married to Pss Charlotte of Monaco.
Duke Franz of Bavaria.
With historic figures trying to determine their sexuality you always have difficulties. Of some we can be pretty clear.
Grand Duke Constantine Constantinovich fathered a brood of Romanovs but also was, according to his own diaries, a religiously tormented bath house visitor.
Prince Max of Baden was passionate with his short-lived first cousin Ludwig of Baden (hinself possibly bisexual), and later with a married man whose wife Max even discretely thanked in a letter for her understanding of his “special friendship” with the husband. Max's "treatments" by Axel Munthe in Capri for his "disorder" were snidely remarked on at the time by Wilhelm II. Munthe twice "helped" the Badens to conceive. If I recall correctly, Munthe is said to have made some tactless references later in life that suggest he may have had to "help" quite a bit with the conception of second Baden child, Berthold.
Prince Paul von Thurn und Taxis corresponded in passionate terms to King Ludwig II and later after their sudden and mysterious falling-out had a failed marriage with an actress who tlater ook a lover and left Paul.
Isabella, the tragic & beloved first wife of Emperor Josef II, left a torrid correspondence (now published) with Josef's married but childless sister.
The name of Italy's charming and dreamy-eyed last King was as early as 1927 associated with several men of obscure and more famous stature. Umberto was four times a father but there was inner circle gossip at the time that the royal conceptions required extraordinary efforts (à la Queen Maud).
And of course there is King Francisco, the Consort of Isabel II, who was specifically chosen by those who hoped to "manage" the young Queen specifically because he was weak, effeminate, and lacking any interest in women or politics. In exile, the couple separated and he lived discretely with his male companion.