The shower curtain doesn’t move while the water is off but when you turn on the shower the shower curtain is drawn toward you.
Thanks for all your helpful answers.I solved the problem by making sure the Vanetion blind over the bathroom window was closed.I forgot to tell everyone that there is a window in mine and my girlfriend’s bathroom.
Answer by M M
The hot air of the shower is rising; the cooler air outside of the bathroom is being drawn beneath the curtain causing it to billow inward. I have found that it is minimized by replacing the rod with a curved rod.