I think that you were not sexual enough with the girl and not pushing for sexYou can get friendzoned whether you ask for a date or not. I’ve been on 5 dates with a girl and gotten friendzoned, I’ve never asked for a date and gotten friendzoned. You really can’t stop it from happening to you, you can be as aggressive as can be or you can be as reserved as it gets and she’s going to friendzone you if she wants to. It’s just a thing immature women do because they don’t know how to reject a man properly.
5 dates and being friendzoned it is quite unusual .
but maybe you did not anything wrong with her , and she just liked your attention and nothing else
you have to be frank with yourself and check throughly if you did any mistake to at least learn from them and not repeat them in the future