Therapy isn’t a test, where the therapist judges you worthy of therapy or not. If you feel you need help, you would benefit from help from a therapist you can work with. Don’t be afraid.
The therapist will guide you through the process. He or she will identify the issues you want to work on, and then help you work on the problem. Depending on the kind of therapy, you might focus on changing behavior to deal with the problems, or you might focus on understanding the roots of the problem, or there could be many other methods.
You should ask the therapists you are thinking of seeing what method they use, and then study that method to see if you think it will work for you.
In couples therapy, the therapist will probably see you both separately as well as together. You probably want a separate therapist for individual therapy. The couples therapist has to be equal for both of you. If you don’t trust that, it won’t work. If one of you is seeing the therapist individually as well as a couple, that trust is easily broken.
My wife and I have been to couples therapy and found it very helpful. I had recently been diagnosed with bipolar disorder and had been unfaithful to my wife. Therapy helped us understand why I did that, and what we both wanted from each other, and helped us learn to give each other what we wanted. Our therapist says that couples therapy doesn’t usually work, in that he usually ends up helping folks get divorced, but in our case, we are still together five years later. I believe it really helped.
As a side note, we are doing what I said you shouldn’t. Sometimes my wife sees him individually. But it doesn’t bother me. I trust him. I trust his impartiality now.