constant delays for meeting up are typically a sign of stalling and/or cold feet.
if you are the one calling off the majority of times, she might assume you are making excuses, making her less inclined to actually meet up.
on the same vein, if she is cancelling most of the times, chances are she is the one having cold feet, especially if the mention of cancelling doesn't include at least the intention of rescheduling.
a text of "sorry, something came up" implies cold feet; "i'm sorry, friday is no good anymore, how about next week?" is more likely a true unplanned delay.
now, these don't have to be true, but they are what is generally assumed