Okay It's A Sexual Question Of Course But Here It

Okay it's a sexual question of course but here it goes. Every time I ejaculate on my girlfriend being her breast,body, or even hands. She has to go straight to the restroom to wash her hands or if it's on her body she has to go wash her body or breast with soap in the shower. Why is this? and causes this? is it me and is it normal for her to have this reaction the longer it stays on her the itchier she gets