It is my experience with those of my kind that they like to talk a lot. It is unbearable but also completely understandable. Most trans folks have kept a large part (too large, in most cases I find) of their personality bottled up for years or decades and are excited to talk it out or explore their feelings with someone other than themselves.
I can't stand it, personally, but I've also caught myself falling into the trap so I can I think relate with some objectivity the dynamic.
So if you can handle it, let them talk themselves out.