Rejection was one of the biggest fears of any human. Rejection from a social group threatens your physical survival; rejection from a loved one threatens your emotional survival.
We had been genetically wired to keep it safe, to keep it under conventional rules, in other words, rules that have been proven already in the past that you can survive if you follow them.
So we keep it safe. It's better this way. It saves energy, the other key factor for survival.
I wonder, in prehistoric times, how was meaningfulness understood by our ancestors? For those whose brain was exactly the same but whose environment was totally different. Since then, homo sapiens ceased developing its genes to develop its environment and all those around them. Living in a cave, with the technology of natural resources and a greater struggle, what were the standards for a meaningful life?
Anyhow, fear of rejection and meaningfulness are directly proportional. The only way to deal with rejection is when the fear of not achieving meaning in your life overcomes the fear of being rejected. Is when you would rather die trying that living longer without having achieved nothing worthy of dying for.
And love? What do we do with love?