If the female kitten does become pregnant, it could be dangerous for her. She may experience complications during pregnancy and delivery, and she may not be able to produce enough milk to feed her kittens. In some cases, the pregnancy can even lead to the death of the female kitten.
It is important to keep the male and female cats separate to avoid any further attempts at mating. You should also take the female kitten to the vet to make sure she is healthy and not pregnant. The vet can also give you advice on how to care for your kitten and prevent future pregnancies.