Cool bike! I can't blame you, I'd have taken it home and I'm not all that into the older steel bikes.

I think my wife and I had 4-500 miles on the Tandem before we learned to not fight each other. We still do a little on our hard and fast efforts, but that's getting better; she just doesn't have pace-line experience at 25+mph efforts. Communicate everything. Drinking, turning, swerving/etc. After time, your stoker will learn to read and feel what you're doing without verbal communication. But until then, you both need to discuss even the smallest of details.