Even if the hemophilia was known?
It didn't stop King Alfonso XIII of Spain marrying Ena of Battenberg.
That's a very serious debate in Spanish royal forums
, did he know there was a possibility (and just dismissed it thinking it wouldn't happen to him) or did he not know at all? The only clear thing is that he (they) didn't know Ena was a carrier, he would have never married her.
I think two of Alfonso's sons did have hemophilia. I don't know if the daughters married, but they were conceivably carriers.
These days hemophilia is not the death sentence it one was, or it once became again for a while during the early stages of the AIDS epidemic. Still, I think people would be very cautions about marrying someone who was the sister or daughter of someone with hemophilia.
The eldest and the youngest were hemophilics. Both daughters married Italian aristocrats, because of the hemophilia threat they didn't have much chances of a royal wedding, in the words of a Spanish royal author "the highest they could aspire to was a Prince of Liechtenstein" It seems they weren't carriers as none of their descendants have been diagnosed with hemophilia.
When we were little and studied genetics in Biology in school one of the exercises we did was to trace the hemophilia through the SRF to "discover" that there wasn't any in the current family