IMO most women aren't really that fun to be friends with if you're a guy. Most of them don't really have the same sense of humor as guys, and likely don't have the same interests.

Generally if you're going to be friends with a girl, she's probably either already part of a social circle you run with, she's not really your type (in which case there's a good chance she might like you), or she acts as a wing-woman to set you up with her friends and/or makes you look interesting to other women in general.

But yeah obviously if she's not interested romantically and you're not interested platonically, then just move on. Don't stick around just to act salty.