Yes, you can write about rape. Saying you can’t write about rape as a subject of fiction is the same as saying you shouldn’t talk about it at all — which is a dangerous supposition to make. That said, you need to look at how you handle rape. Is it just another plot point? Is it exploitative? Is it an easy and lazy crutch in a genre where it’s used too often? Is it made to be more titillating than horrific? Rape is not just a throwaway topic. Realize that some of your readers may be the victims of sexual assault. Consider how you want to speak to them as your audience and how you want them treated in your fiction.