I just don’t get it…

I just don’t get it… I could talk to myself all day long when I’m home alone and my fluency is great, but the moment I have a listener when I’m speaking, it’s gone… It’s genuinely frustrating that I’m so well spoken when just expressing my thoughts to myself out loud, but I can barely get through a few words without a block if I’m having a conversation. That’s life though I guess.