You can write a marriage with drama in it. That's half of the drama in the Americans. Looking back on Young Justice, it was able to not only have the kind of romances that are in the Arrowverse, but also have them make sense. When there's a break up, it makes sense given the circumstances. Nothing felt shoehorned in.
And it actually kinda makes me sad. Young Justice most likely had some of the best romance i have ever seen in a cartoon, or serie of its type.