An SO will align their goals with you. A best friend may find another goal in life and go off on their own. A friend isn’t tied to you, and you’d support them if they ‘leave’ you to seek their own fortune. A partner stays with you and you and they need to find ways to reach your goals together. There’s a stability and security to a partner that you don’t get, no matter how close your friend is.
I’m in my mid 30s, having women tell me of the psychological fights that NO ONE TOLD ME WERE EVEN HAPPENING, AND NO-ONE GOT ME.
Anyway, I now have a great love life. So long as you’re not dead, there’s always time for it to sort itself out. Be patient and focus on yourself.