The therapist MUST be in an appropriate mental/emotional space in order to be fully present and able to engage with the client. If anything in her life is interfering with that ability, it is her ethical obligation to NOT see that client.

Let me use a really dumb/obvious example: Let's say you are an actively using cocaine addict and you are engaging in every coke addict thing in the book to avoid the issue. Now let's say your therapist lost her child to cocaine overdose a few months back and she is in total internal uproar.

Should that therapist be working with you? Absolutely not. It would be unethical and quite possibly harmful. It's not about you, though. It's about her.

That's the way the rules of the profession work.

I hope that helps it make a little more sense.