I remember as a child feeling very lonely and left out because their love for each other was a closed circle and there was no room for me in it.
I had a much different family dynamic. I never felt that there was any love between my parents at all. They never touched, hugged, held hands. My father seemed to love NM, but she did nothing but express contempt towards him. She treated him like dirt, talked down to him, told him he was worthless, and he just nodded his head up and down like a puppet and said "yes dear." As my parents got older, NM started telling him that she wished he would hurry up and die so she could have the house to herself. She would constantly say things like, "I picked out the new furniture myself because I want the house to look the way I want it to after your father is dead." She would say this right in front of us, AND in front of him, and he never blinked.
When I was growing up I was certain that he would divorce her after the kids were grown. I couldn't imagine anyone WANTING to be in a relationship where they were treated like some kind of waste product, but nope, he has stayed with her for 50 years, and is more than happy to be treated like trash. And to routinely throw his children under the bus to protect her . . . I'll just never understand that.