Behavioural can also be the thoughts you tell yourself about something that happened in the past, if that makes any sense? I was having a lot of trouble relating to a family member and a lot of it had to do with confusion/guilt/anger over abuse in my past. We also work a lot with acceptance/commitment but talking about it and trying to kind of find ways to reframe the past was part of it. Learning ways to stop constantly blaming myself for everything and understanding what happened to me as a child (understanding properly as an adult) before moving on and finding ways to deal with the relationship now.