Is it because I watch and read too much yaoi? I mean, I'm like ''Aah how cute'' when I see a gay couple but when it's heterosexual, I have a weird feeling they don't match and I should pair them with another man and woman instead. Like, imagine a pretty girl with long floawing hair and a handsome boy sitting somewhere like a forest, it seems weird. Look at this Hetalia fan art of PruHun (Prussia x Hungary, it's about countries):
Those are mainly two boys, that long hair and stuff is weird to see.
Most Helpful Guy
It's possible that you are having an issue with the visual imbalance, typically a guy is about 4" taller than a woman. men also typically have broader shoulders, while I find that this visual balance makes a male-female relationship more aesthetically balanced than either a male-male or a female-female relationship, it is very possible that you find the differences to be the issue.
the other possibility is that you are actual homosexual and find it odd to see a relationship between genders. this would be enhanced by your predilection towards yaoi because in you preferred fiction you see mainly male-male relationships.1