It protects her very sensitive clitoris from getting hurt and is similar to your foreskin [ 1 ].
Of course this all includes very good hygiene.
However, your goal should always be to use the minimum amount of pressure possible to make her cum when you are eating her out.
The anal sex guide should help you out too.
Again, spend some time on other pleasurable, but non-orgasm-inducing activities until she has calmed down.
Eat me till you taste my juice
The only other reason is that she simply may NOT enjoy the thought of you eating her pussy. Did you ever consider that possibility? Here are just a few examples of how you can get your hands involved. Yesterday i licked her body then to her pussy for about 20 mins. The wetter the better women love to be fucked with the tongue.