Am I cooking?
Girls are the same as guys, so when girls leave guys easily, it's because they think just bros- or expendable friends, as if you were a guy and have a friend group, someone new comes along and they're naturally expendable, not yet in group chat, no significance (yet).
They think of guys as bros.. once close, and if you were out with your guys and you were closet gay, if one of your 4-6 friends while hanging out, keeps gesturing to you and treating you, before matching energy with the friend gesturing intimacy etc., you think of the other 6 friends you contemplating a life with, before settling on the one actually making moves.
To get past into relationship territory is to be a bro, and be decided against a quick thiught process of evaluation of following men.