There's a difference between causing you to feel bad, and not stopping your bad feelings that originate somewhere else.

Your T isn't going to do anything to purposefully make you feel bad. If she or he did, they would be terrible T's. They're not going to purposefully ignore you, knowing it makes you feel bad. They may have boundaries they're sticking to, but that isn't in order to make you feel bad. That's just their rules and boundaries. They're also not purposefully saying things to trigger or hurt you. Those are simply mistakes or things they don't realize will hurt you.

But your T isn't going to interrupt your bad feelings about them or someone else. They're there to help you learn to deal with them and get them out. For example, say that someone died and you feel grief. Your T isn't going to do something to interrupt that grief. In fact, her goal will be to make sure you get in touch with that grief and feel it. Another example is with childhood abuse. Often it makes your emotions go numb. Your T is going to want to get you in touch with your painful feelings from the past, not continue to allow you to run from them.

Your T won't do anything to purposely hurt you, but they also won't stop you from feelings the feelings that other parts of life, past and present, have caused.