I talk about sex a lot with my T. I never did with any previous T (I was too shy) but my current T makes it relatively easy to talk about. I think it depends on the T. Mine asked me questions about it early in therapy, and I was surprised, but I was kind of glad that she asked. You can tell your T you don't want to talk about it if you don't want to. Or you can ask her why she keeps bringing it up.