* Early Episodes: Tamaki is initially infatuated with Haruhi's "mystery" and enjoys teasing her. He sees her as a challenge and is captivated by her unconventional nature.
* Episode 14: This episode is a significant turning point. Tamaki, despite initially wanting to maintain his facade, starts to feel overwhelmed by Haruhi's presence and her connection with the host club. He shows jealousy when she interacts with other boys, indicating a shift in his feelings.
* Episode 18: This episode is when Tamaki's feelings become more apparent. He finally acknowledges his feelings for Haruhi and confesses his love for her, even if indirectly. He also displays a strong sense of possessiveness towards her.
* Later Episodes: Tamaki's feelings continue to grow, and he becomes increasingly protective of Haruhi. He also starts to develop a deeper understanding of her true self.
It's important to note that "Ouran High School Host Club" isn't a typical romance anime. The focus is more on the dynamics of the host club and their interactions, with Tamaki's feelings for Haruhi unfolding more organically and subtly. While there's no single "aha" moment, it's clear that Tamaki's infatuation turns into genuine love over time.
Ultimately, you can interpret the series as you like, and many viewers feel that Tamaki's feelings become evident throughout the series.