How ??? Seriously how ???

How? Because the one doing the catching said ‘fall and I’ll catch you’ but didn’t specify which way to fall. The falling person made a mistake from vague instructions, by assuming she should fall forward, like you do when you fall over walking or running. A plausible assumption. But the catcher can’t be fully blamed, the faller did not clarify the instructions. There’s a lesson here for us all. That lesson is communication is the key to success. And to assume makes an ass of u and me.