If you want somebody to love you down to the core, you have to let them know you down to the core. You have to risk being rejected.
Likewise, if you want to love somebody down to the core, you have to get to know them down to the core. That looks like spending time, practicing patience, learning tolerance, and accepting somebody unconditionally.
Being loved down to the core and loving somebody else down to the core require that you know and love YOURSELF that way.