Here are the most common things I see people beat themselves up for not knowing or being good at:
How to handle conflict.
How to know your feelings.
How to connect and talk about feelings with other people.
How to set boundaries for how others treat you.
How to ask for help.
How to assert yourself calmly for what you need.
How to follow your own path.
How to love someone without losing yourself.
How to stay married.
Here's the thing. If no one ever modeled those skills to you as a kid, if no one ever showed you how to do them ... how would you have learned?
Here's how: you taught yourself.
But you know what else? Any of those things are just skills you can learn any time you want. You can get help in ways that work better for you as the adult you are now. From self-help books, podcasts, mentors, therapists ...
You can learn all the brand-new, shiny emotional and relationship skills that make your life more fulfilling any time you want.