Realism might be considered the opposite of Romanticism.
Consider the elements of Romanticism (although, since there is no real "romanticism manifesto", we might say that these are properties observed and categorized after the fact, rather than as distinct intentions of the creators):
-Romanticism is a reaction against a perceived loss of emotional expression due to the materialism in the modern social and scientific world.
-Romanticism values originality, spontaneity and passion.
-Romanticism is concerned with feelings rather than facts; in fact reality may be freely distorted to suit the artistic purpose, and rules of organization are considered limitations and are to be avoided.
Realism contrasts with these values. Realism emphasizes, unsurprisingly, the real world. It is sometimes noted for its portrayals of ugliness or filth, and is sometimes appropriated, such as by the Soviets, to glorify the common person, working class, or the poor. More generally, it saw pointless artificiality in the idea or depiction of the supernatural or heroic, preferring to find honor in reality rather than soullessness as the Romanticists did. Additionally, Realism frequently treats human subjects rather than landscapes, as Romanticism often did due to its tendency to focus on nature.
Realism is known to be the opposite of romanticism. There are a lot of aspects that make these two genres different from each other. One difference is that romanticism is focused on plot while realism focuses more on the character and uses the plot to back it up. Another big factor is that romantic novels use a lot of metaphors and exaggeration, making the story seem more like a fairy tale. Realism shows things how they happen and don't fluff up the story. Realistic novels are in chronological order, showing the story as it actually happens and romantic novels focus on characters feelings and hopes rather then reality.