Ina is too shy to talk about her feelings to anyone even to her best friend Jeongin. Hyunjin on the other hand doesn't have a filter and expresses his feelings just not to Ina.
Jeongin and Chan have been best friends since 10 years and Chan has feelings towards Jeongin but he hides it so well.Hyunjin basically have a bet to do where he has to make Jeongin fall in love with him but he ends up falling for Jeongin.