Mind readering. Ugh.
You gave her the chance for an "out" when you realized you didn't get a solid yes from her.
How about apply reassure? And let her own her yucky feelings? Be supportive as she deals with them, but don't
play mind reader games. Maybe something like...
"I am sorry it did not go how you wanted it to go. I see you are hurting and I want you to know I do love you and I want to be with you.
I offered to cancel it if you were not comfortable. You said you were ok so I believed you.
I cannot mind reader you. Thank you for telling me now. I expect you to continue to tell me things you want me to know. This is good. Now I know what you want next time.
For what it is worth, I thought it went fine. J checked in and she thought it was fine. So if this is about anxiety with a new thing... you were lovely. We are all learning how to be together here in a new way.
I love you and want to be with you. How would you like to move it forward from here? If you need extra reassure in the moment? What's our bat signal gonna be? Squeezing my hand? "
Offer her a face saving "out." Hug her to reassure. Tell her you are willing to meet her needs (on this thing) now that you KNOW them. Tell her if she lets you know what other future things are you will try to meet them. But you like knowing BEFORE if possible.
Then let it go and expect her to TELL YOU things. You do not mind reader.