Well we won't really know because Hwa was marked very young. His fate was decided the moment his family moved back to Korea. If they had stayed in America and he never returned, there might have been a chance he could have hooked up with someone else. Not sure if it would have been another werewolf or vampire but outside of those, it could have been anyone.
But I think Hwa was attracted to someone who had already marked him as a mate. Males can mark too. So in theory, they could have met and fell for each other more naturally. Maybe they did (as kids.) But that isn't something we know.
But wasnt it the same case for the main couple? So far all its shown is how "natural" it is to fall in love between a male and a female and i mean, the media pushes that a lot already. For me gay stories shouldnt be just about dongs but also about unlikely circumstances n stuff, and seeing how the second pairing has the same basis at the first, dunno man, it just seems like the semes are puting up with being with a male body because female lycans are "so rare"
(Just looked up the main couple's names and realized Hwa's "mom" is Hwa Gok...)
Hwa Gok's grandmother was female and a female lycan. So they can be female-female as much as male-female, maybe. And the main couple is involved with an active circle of people in contact with the lycan-in-charge of this whole breeding thing. It wouldn't be a stretch to say the second couple was more likely to meet because of this. Looking back at the very beginning chapters, Hwa Gok and Lee Bin do seem reluctant to be together for a long period of time. I don't get that with the second couple. Hwa seems very bi to me and Seol up until that point seemed aloof as his family was one he was supposed to "marry into" and he had kept his memories. The interest was there before they started going out, at least.
This female shit i swear, the str8ts are wining even in a yaoi manga coz basicly hwa would have never went for the uke if he wasnt "female"