I'm both a couples therapist myself AND I've been to therapy with my husband.
So I've been on both ends of the scale, which has been challenging to say the least. It's not easy being a therapist and having to admit that you need help too.
As a therapist, I have a few methods that work really well. I personally love working with the Gottman communication principles. However, when communication is only scratching the surface and there are deeper issues, I often use EFT or Stephen Karpmans Drama Triangle theory, wich really helps me get to the root of the problem.
When my husband and I did therapy, what stuck with me most was that just understanding what was happening, wasn't going to fix us. We had to be willing and committed to make very real changes, which would require a very real effort from us both. It helped us both get out of our victim mentality, where we were constantly blaming each other for the problems and passively waiting for the other to change. Therapy makes everything more circular. So to elicit certain behaviour, you need to bring the right energy to the table. Every toxic dynamic can exist only because it's a mutual invitation that has been accepted on both ends. And it takes a joint effort to step out of it.
What also helped me personally was recognising that I have a pattern of going in flight-mode. Whenever something gets hard, my mind immediately goes: I should leave him. And that this thought is not what's best for me. I can recognise it when it happens now, and still choose to stay actively engaged in working through the problem, rather than shutting down. To do that, I've made a very conscious choise that leaving my marriage just isn't an option, and that I have to make things work with the husband I've got.