>>91328686because when it comes to the first person she has started to fall in love with, she's clueless how to handle these more-intense-than-crush feelings
and she doesn't think Marco reciprocates her feelings and is terrified of losing her best friend
so while she's comfortable flirting/checking out/whatever other dudes, when she is confronted with serious feelings, she panics
stuff like this happens in real life-I'd say it's even a trope to have a dude/girl who is a massive flirt/sexually aggressive towards many others/people they're physically attracted to, but when it comes to the person of their actual deeper affections, they spazz out and short circuit and do dumb things
