If you don't feel like you can ask him the question, can you talk about your reaction and feelings about the situation? He may answer the question anyway, or you may find another way to deal with it.

There's been times where I was sure something was going on with my T and it was affecting me...either my trust in the relationship, or my worry about her, or my feeling like I could come in and "unload" my crap because there was something there on her end...an elephant in the room. I didn't want to ask her anything personal or make her feel like she had to tell me if something was or was not going on, so instead, I started to just address my reactions...how I felt, my perception, how I was processing it. Most of the time she has stopped and thought about it and said yeah, your right, there is something going on and she'll tell me what she's comfortable telling me about it.

Whatever this is with your T, it's obviously affecting you. Could you find another way to bring it up if you don't want to ask the question? Maybe even telling him you've been cancelling because there's something bothering you in the relationship/in the room or however your feeling it, but you don't want to intrude into his personal life by asking a question he is uncomfortable with so you don't know how to address it. Just a thought. It's worked for me because I'm very hesitant to pry into my T's personal life...but if it's affecting your therapy, then the part that is about you is important to address.

I don't know if that makes sense. It's hard to know exactly what to say without specifics.