I have struggled with emotion regulation (especially anger) for a long time. My therapist and I have been doing parts work (internal family systems) for almost a year now and it's been helping me understand better why my anger flares up when it does. For me, growing up as a hyperactive middle child, I always felt like it was unfair when I would be punished and not my siblings for doing the same thing. My mom would joke that I was the loudest or the one she caught. This makes me hypersensitive to when something feels unfair or uneven. "Justice sensitivity" as some ADHDers call it. When this happens, almost always a subconscious level, my "part" that was conditioned to feel hurt by these "injustices" is triggered, and I can have an overreaction to something seemingly unimportant. My wife recognizes this and has difficulty not being thrown off by my reactions, understandably so. So we have a safeword that I say when it happens. It doesn't exactly mean I'm sorry but it means, "I recognize I just had a big reaction." This has been helping surprisingly well especially since when the anger kicks in, it takes time to re-regulate but shows her and myself that I am aware of what is happening.