Why does society view the desire for infant-like comfort as a negative trait in grown-ups?

How do you deal with friends who think you are overthinking when you try to warn them about a bad situation?
Why would my narcissist ex start dating my boyfriends ex? She is not the type he has ever gone with before, and never spoke to her until I started my relationshio with my new partner. Why?
What's the difference between healthy compromise and dragging a partner along in a one-sided relationship?