People often complain that Ayn Rand's characters are unrealistic. This is false. There are various reasons they are confused including denial and evasion about what the world is actually like, and trying to instead believe fantasies.
There is something about Dominique, from The Fountainhead, which is uncommon but not unrealistic. I see why it confuses people. Her actions in the book, like marrying people she dislikes, strike many readers as fantastical. They are missing the point. Dominique's ideas are not fantastical. Many people have stranger ideas. What's unusual about Dominique is that she actually lives according to her ideas. While making major life choices according to one's ideas is uncommon, it's not unrealistic or impossible.
Most people have all kinds of strange ideas. Actually it's much easier for them to have bizarre, weird, or extreme ideas, because what difference does it make? Since they don't live by their ideas, they have less incentive to work on making the ideas any good. Most people, whatever they think, won't stray too far from what's normal. To them, thinking is a bit of a game, but when it comes to the important things in life, they conform. Dominique doesn't.
People think Dominique's ideas set her apart, but it's the part where she actually acts on them that's key. Plenty of people would stand out even more if they actually lived by their own ideas.