> Relationships are a huge competition in an atomic family type situation - children competing with spouses for time, spouse/kids competing with grandparents, family competing with friends... and god forbid if you have a family member with medical needs.

Wow, I have never experienced competition in that situation. There are scarce resources at times, but that doesn't mean they are distributed by competition. IME, usually people work together toward the greatest good for the family. They love each other and want each other to thrive, and would generally rather sacrifice themselves than see a loved one sacrifice for them. That good faith is never in question.

The question is not of good faith or the competition being overt or malicious type etc. Time is finite - if you are spending on one side, you can't be sending on the remaining sides. Usually the people in your life realize it and adjust for the priority/greater good and so yes, they will willingly sacrifice in that spirit. But the relationships themselves are emotionally competing - if you have, e.g., to choose between relocating for the future of your kids and your ailing parents, those duties are competing, even though the recipients themselves may not be - you will have to choose.

I was thinking about the establishment of peer groups and identity in teens, but you are right that there are other forms of relationship competition.