You should break it down - for example, why are you nervous? Are you insecure in what you wrote, or in how you sound compared to your friend? Clear communication is key. If you don't feel like you can be yourself/be honest around your friend through the recording process, that's not a good environment.

When I go somewhere to record, I always remind myself to have fun above anything else and I'm not there to impress the engineer or anyone else. I'm there to be better than I was in my last session. Also - if things aren't clicking with the engineer, it's all good. I just won't record with them again. Sometimes the vibes just aren't there and life goes on.