I know you know it's okay to like both men and women, but I wanted to say how lovely I think this interaction between you and your T is. It sounds like you are making really positive changes in your end of the T relationship and seems like you are really benefitting by making these changes. It's good to read about therapy working in this way.

On the "open relationship" issue, I have learned by interviewing people about all kinds of personal and sensitive issues that labels are used differently by different people. I would have asked what that means in your T's shoes, not because I am unfamiliar with the idea of a non monogamous relationship, but because people mean different things by it. One person said he had an open relationship but his wife didn't know about it, which was his way of saying he had affairs. In some open relationships there are rules about with whom or when a secondary relationship can take place, the rules can be different, etc. I think your T was just trying to get a sense of the lay of the land of your relationship with your SO. Kudos to you for being so open about your sexuality with your T. It can be a really hard thing to do.

I told my T recently I was considering beginning to date again after my last round 25 years ago, when people had to call each other on landline phones to schedule dates. He said something that was gendered, and I said I wasn't necessarily looking for a man. He replied, "good, then the dating pool has just doubled," and that just cracked me up. It wasn't all that long ago that the mental health system considered anyone who wasn't heterosexual and gender conforming as pathological (and locked up young people in institutions for years); it's good to see that T's can be open minded and accepting.