Thank you NYCindie,
I was hoping that someone as experienced as you would answer. I know that the stuff about the "vanilla club" sounds odd, but I don't want to name the activity because it is not that hard to connect the dots.
What you suggest is quite reasonable, and what scares me is that things went so well initially that I am a bit afraid to mess them up.
Yes, she did not show up two time in a row but as far as I gather, she has plenty of things to do in her life and the club is not her only activity. I have been going there over the last couple of months and she was there no more than four times total.
CielDuMatin, thank you for the comment. I think I will keep the poly stuff out for now because I suspect it is alien to her. I agree with your comment about making an "omission" but I want to reach a stage where she would at least listen and let me explain myself before making her decision.