I guess this is a silly question. Males and females used to drink from the same cup when the Church had communion in both species. Of course, they still do this in the Novus Ordo, but that doesn't count.
I guess it felt weird because I was nervous about some kind of flirtation that might have been happening under the surface. Which as far as I know, didn't happen.
Also, I said "unmarried" when I really meant not married to each other. But this woman is married. I am on my guard for obvious reasons, hanging around with a married woman. I'd say "overly on my guard" but then you really can't be overly on your guard in such cases, can you?
But that doesn't change the nature of my question about using the same cup! Anyway, she's a Prot, and I'm trying my best to set a good example for Catholics -- who she thinks are horrible sinners -- so I'm glad I didn't act out of scrupulosity if it wasn't necessary.