I agree with Argonautomobile that she probably didn't want to risk crossing a boundary or risk sounding intrusive on that topic.

I was supposed to talk about sex this week with my therapist (had written about my intentions in an email) and I didn't. At the end of the session my therapist asked me why and I told her she should have asked questions to prompt me. To which she replied she didn't want to sound intrusive.

Sometimes therapists think they have to be super careful, especially about such a sensitive topic.