Searching for a manwha

The mc is a girl it's a romance manwha. So the girl had a crush on a boy in highschool but in the end he was gay and so they just are bff now. She thinks of herself as a gaydar girl or sum and in college meet a popular guy who's girlfriend was stolen by his sister once or something. And they're basically in love I think but both think that the other one is gay.
Please help me I beg of y'all.