What makes a relationship romantic?

Trust: Trust is the foundation of a romantic relationship. It’s essential to feel secure and confident in your partner’s commitment, loyalty, and reliability.
I recently finished a Cara Devlin novel, ‘Nature of the Crime’, and one of my favorite scenes came near the end, where the main male character rescues the female main character. Even though it wasn’t expressed, I had such a strong sense that she wholeheartedly put her trust in him. He would find a way to help her, and she was not surprised when he did. This is a point in most romance novels that I find hopelessly romantic.