My therapist explained it like that. You have certain reactions and feelings to certain triggers or environments. By going to the therapy you talk about it, figure out why do you react in a certain way and eventually you developed new neural pathways on top of those old ones with unpleasant reactions. But this is for psychoanalysis, other types might work differently, but general idea is similar from what I understand.

Also this is normal to go through a huge amount of therapists, mine said that finding a fitting one for you is about as hard as finding a perfect wife/husband.