Anime: Peach Girl

Momo has had a crush on Toji for years, but has kept it a secret for years on account of a rumor that Toji considered dark skin and blond hair to be a turn-off. Her first time telling someone about this crush was during the course of turning down Kairi, unknowingly within earshot of Toji and Sae. Toji confessed his love to Momo, they got together, Sae used assorted Magnificent Bastardry to try to break them up and generally make Momo's life miserable, Kairi consistently proves a Spanner in the Works to Sae's schemes, and Momo starts falling for Kairi.

And it gets even more confusing from there.

This show provides examples of: