as in why do you women get pissed off either way when you find out you are or are not pregnant?
It's complicated. I can tell you there were times when I was trying to get pregnant and found out I wasnt. I experienced a huge loss each time, which included being pissed off. Is it rational? No. But that's the way it is. Bringing another life into this world is serious business.
I've also had a couple times in my younger days where I thought I was pregnant and didnt want to be. I met an adorable fellow working at a summer camp while in college. Thought I was pregnant. I remember sitting in the bathroom crying and praying- please god, if you make it so I'm not pregnant I'll never have sex again. Turns out I wasnt and I went right on having sex with him. I'm going to hell.