Any manga/anime where the male and female leads date. The female lead falls for another guy and breaks it off with the male lead. Eventually she realizes she still loves the male lead and then eventually get back together.

Ex: Bitou Lollipop

Madoka dates Tomoyo, but then falls for resident piece of shit Ono. She tells Tomoyo she only thinks of him as a brother and that breaks his heart. Eventually after it doesn't work out with Ono, she realizes that she is in love with Tomoyo. They eventually get back together.

The only mangas that I think of are:
Sunadokei
Chitose etc, but they dont go out at first romantically (But they both want), then she dates another guy and then come back with the first guy.
In Peach girl the girl starts with one, then dates another, to date the first one, to end with the second one...