You should always be carefull as a girl when riding on top of a big. Especially when you get close to an orgasm, you lose control over your body, start riding rougher and faster and this can lead to painful injury`s like this girl finds out. The dick slips out of her pussy and touches her on a apparently sensitive spot and it makes her cry. But you can also hurt your partner, he wouldnt be the first one ending up in hospital with a broken dick.