There are others.
One of the most popular romance manga going right now is The Fragrant Flower Blooms With Dignity, and its main couple gets together fairly early.
It's only a conflict in the sense that that Yuu is Umi's best friend, so Umi doesn't want to hurt her. Neither does Maki. However, it's clear that Maki is not interested in being with anyone but Umi, so the conflict is just figuring out how to navigate the situation and hope they can still be friends with her.
A Condition Called Love, was the series i was thinking of. It happens quite late in the series so thought I’d mark as a spoiler. Not quite the same but Skip and Loafer also features something similar