Ohr chodesh:
There certainly are therapists who can damage. There are rotten apples in every bushel. However, very, very few rabbonim have the extensive experience with shalom bayis issues you expect, and that makes the average Rov, unless you know that he is the exception, NOT qualified to advise or direct. Any decent therapist knows their areas of expertise. If they do not have the experience to work with addictions, they redirect referrals to someone that does. Same goes for any other area. Being mesader kiddushin at a chuppah does NOT qualify to give advice on marital issues. And I proclaim loudly, the same goes for chosson and kallah teachers, who have racked up horrendous records of ruining marriages if they are asked for advice after the marriage.
I once asked a well recognized and respected Dayan about a certain chosson teacher. Once identifying who it was, he turned and spit on the floor. He said to me, “You know of a few cases of casualties of this man. I know of many dozens.”
Smicha qualifies one to pasken shailos. It goes without saying that there has been shimush by veteran and seasoned poskim. Now, please tell me, what qualifies that Rov, big talmid chochom, etc., to counsel anyone about anything? Training? Shimush? Any Rov challenged with a problem will want to help. If he believes he knows what to do, though with no experience, he runs a risk of harming equivalent to a grocer practcing medicine and surgery.
I direct you to the peirush of the Ramban on Bava Kama daf 87. (Hard to find – it is the only piece of Ramban on Bava Kama and thus missing in most sets of Ramban on Shas.) He is clear that practicing any form of health care without proper training is assur. I await your reply after you have reviewed that Ramban.