No love triangle Mako (Female Lead) only ever has feelings for En (Male Lead) and never thinks of the other men romantically. She has a flirting personality which is because she wants people to love her and care about her but she quickly stops putting up that act. She does blush around the other guys but that's because she's happy to see them smile, other times she does is because they say something that reminds her of something En did. Hope that helps and didn't ruin the story for you.
P.s. The Long haired guy does want to wow Mako but she rejects his advances. Or "Ruins" his flirting.

i wanna reaally read this, but for now im curious, who is the other guy? the one with the longer hair
is this a triangle love kind of manga?