Hey girl
First of all, I know how hard it is when you want intimacy but are still pre-op. It is also the reason why I am not really dating actively because it will at some point come down to this. It is just awkward for intimacy when you want to be with someone but that just gets in the way
However it also seems to me this man is willing to overlook that and be with you, so I would just let myself go and wear some tights which can prevent things from getting too awkward. He obviously wanted to be with you bad. If you are unable to relax with this issue, then my advice is wait for the operation to be completely free inof your mind if that is what is necessary. Or change your mindset, enjoy it while you can and try not to think too much. Stress raises T levels so when the body is tense, erections are more likely to happen. I can't talk about that since I have been on t blockers and that thing doesn't happen really. But I understand how being pre op can be a problem.
Hope it's helpful