This has baffled me for years... For example, here's one that happened to me recently.

It was my LTR friends birthday recently and she planned to call all her friends and go for dinner

LTR:(Name of friend) called me today and invited me to her birthday dinner but I feel so sick, I've a cold and feel terrible. Plus (name of another friend of hers) will be there and I hate that bitch I haven't spoken to her in a while and also I don't like the food that restaurant serves(It was a Chinese food).

Me: Well okay than babe don't go...

LTR: Yeah... I guess so...

*Next day she's goes to her friends birthday dinner

WTF why do women do things like this?