I have done this a lot. Makes me wonder if it’s from sexual abuse/trauma

Most of my fantasizing during sex has been not me, meaning I’m someone else...sometimes so it my partner...in my mind...also: sometimes I’m just fantasizing about my mate and someone else...I’m not even involved at all...
I realized it felt most of my life like I wasn’t actually consenting...or at least not participating...I was giving passive permission for something to be done to me, not being an involved partner.