Sometimes, it's a plot device to create tension. A scared heroine adds an element of mystery and drama. The author might use this to gradually develop the relationship between the two characters. As the story progresses, the hero can then work to gain the heroine's trust, making the romance more interesting.
One common situation is when the hero has a secret. If the heroine senses that the hero is hiding something, it can make her scared. For instance, if he's part of a dangerous undercover operation but she doesn't know it, his evasiveness can be frightening to her.
Redemption can be a theme. Maybe the hero has a past that makes him seem more threatening, but as the story unfolds, he redeems himself in the eyes of the heroine. Also, the theme of love conquering fear is quite typical. Despite her initial fear, the heroine gradually falls in love with the hero, showing that love can overcome her apprehensions.
The development can be aided by the heroine's own growth. As she gets to know the hero better, she might realize that his dominance is not all bad. She could start to see it as a form of strength that can be beneficial for them both. And if the hero respects her boundaries and is willing to step back when she's really scared, it can lead to a more positive relationship.
These novels often explore the cultural clashes and fusions. The Asian heroine may bring in elements like Asian values, family concepts and traditions. For example, in some stories, her respect for elders and family loyalty add depth to the plot. The white hero might represent different Western ideals. Together, they create interesting dynamics as they fall in love, facing challenges from both cultures and society at large.
They offer a sense of innocence. It's like seeing love in its purest form, untainted by past experiences. For example, in many such novels, the characters are experiencing love for the very first time, and that makes their emotions more intense and relatable.
It could be that the hero is so focused on other goals, like achieving a great career or avenging a wrong, that he doesn't have time for the heroine. He might think that romance would be a distraction from what he really wants to do. For example, if he's on a mission to save his family's honor, he might see a relationship as something that could get in the way of his pursuit of justice.
Maybe she has had some bad experiences related to so - called heroes in real life, which makes her cynical about the idealized heroes in romance novels.