A therapist may ask to adress the issues that you don't want to discuss, but if you don't want to discuss them then it is really up to you. It is the client/patient that is really in charge of the therapy session. The therapist is kind of just there as a guide... He/She will help guide you on what ever journey you want to go on... (I know that sounds kind of stupid, but it is the best way I could think of to describe it)...

Hope this helps some,
Jason