I have a very hard time opening up to my T. It's kind of a catch-22 situation: I can't open up until I have known someone for a long time, but if I go too long without telling T something it feels like I just shouldn't say anything for fear of looking like a liar, I guess.
That said, there are many things I don't tell T just because they're not relevant to therapy and so I don't want to spend my precious time with her on them. I don't think I've ever spoken to her about relationships, church, my sexuality, etc... but if one or some of those things began either to affect me or become affected by my mental illness then I would try to bring it up if I could.