Is it customary for the boyfriend to give his girlfriend money every time they go out?

I notice that almost every time we go out, my girlfriend always asks me for money and I give it to her. As a matter of fact she told me that a good boyfriend should just give his girlfriend money every month even if she doesn’t ask. Am I being taken advantage of? Do you guys give your girlfriend money every month? Would you girls love your boyfriend better if he did that?