Two friends (Female and Male) from high school make a promise that if they reach 30 yo, and if they don't have a couple at the time, they'll become a couple and marry
https://www.mangago.zone/read-manga/even_if_you_don_t_have_a_third/this maybe?
Yes thank you!
Two friends (Female and Male) from high school make a promise that if they reach 30 yo, and if they don't have a couple at the time, they'll become a couple and marry