Sometimes deciding what to research can be very difficult! Researching sexuality topics can pose a few additional difficulties. Some people get nervous discussing intimate topics. Some people are afraid that they are studying something for a personal reason. Sometimes, the research is for personal information but often it is for the sake of interest.
But, in general, the research process is most rewarding when we are learning something new and different. As with anything, don't hesitate to ask questions. A principle of librarianship is to answer topics and questions without judgment.
If you are having trouble finding a topic, there are a few sites that offer a lot of information on sexuality issues. You can look at these sites and brainstorm topics.
American Psychological Association Sexuality Topic page