The difficulty is that I am so pleased that he has done this the right way round in terms of expressing a need and telling me clearly what he wants that I really don't want to just say no.
Is it possible for you to say something like --
"I am really pleased you have asked me up front like this. I'm pleased that you clearly expressed you wanting me to come along to watch, were willing to give me time to think it over, and were prepared to accept my decision. That part was AWESOME!
I have to say "no" because it really isn't my cup of tea though. But keep asking me like this! I love it!"
If you are a person raised to put other people's needs/wants ahead of yours it can be hard to learn the difference between "selfish" and "self full." Other topic, but perhaps reading this post
helps you with the (selfish -- self-full -- selfless) thing.
I think you could meet your OWN need for (I need to feel emotionally safe) first, and then whatever else you do for others after that can be a gift. Rather than a chore or oblgiation or worse -- meeting other people's stuff before yours and running your own self dry.
"Self-full" to me is meeting your own needs and the needs of others in a balanced way. Put your own oxygen mask on first -- after that help whoever else. This is not being selfish. This is necessary! If it were an actual plane emergency, you can help a lot more others having put your own mask on first than trying to help and kicking the bucket because you ran out of air from not attending to your own need to breathe.
It's ok to "wobble" -- but you are not doing anything horrible in trying to meet your own need (to feel safe) above his want (come watch me do a scene.)
Wants are not needs.
If his need is to feel close and connected to you, it can come about doing something other than you watching him do a scene. To be close in that form is a WANT to me. The NEED can be met doing something else to me -- go bowling, have dinner out, catch movie -- whatever thing you BOTH like doing.