A guy can see the red string of fate, which link soul mates together and one day he notices his is linked with someone, but instead of it being to the girl he has a crush on it's linked to a boy. He runs into him a lot and the boy falls in love with him and confesses but the main character resists him. The whole resisting destiny plot. The characters are both super cute, even the tsundere main character. I want to read more!
Akai Ito No Shikkou Yuuyo