It’s commonplace that even Frum therapists see opposite gender clients and I’m sure they do this with Rabbonim’s okay.
Many therapists specialize and the help that individuals need is sometimes special. So it ends up that most therapists have opposite gender clients.
I sometimes wonder about some posters here -Do you just sit in front of your computers all day on your thrones and decide e/o out there is doing something wrong? How about going out once in awhile and seeing the world? Yes, Professionals deal with e/o even if they are Not the same gender.