Noob.. My wife and I have many miles on tandems.. 10's of thousands of miles. We currently own 3. Until this past year almost all of our road riding for the past 18 or so years have been on tandems. As well as some off road riding also.
hmm I am not sure how to put it..
I don't mean to talk down to you at all.. I don't recall what you know and what you don't.. so If I mention anything you do.. I apologize.
Tandems can take time. I have had a lot of friends that see how well my wife and I do on our's and want to try it. It has proven to be harder than they thought. In selling tandems.. we were first taught to take the Capt. out for a ride [with him stoking] and scare the crap out of him.. then instruct him. Then take the would be stoker out for a good ride.
A couple does need to be able to work as a team. A stoker that has control issues or trust issues, will always have a hard time. In most cases the stoker can not see up ahead.. so that can't see where they are going, and they also have no control where they are going. I have stoked with other people also.. and I must say even after many miles captaining a tandem, it was a little unnerving at first. To be riding inches from the edge of the pavement.. and to not be able to see where you are going.. or to have any control. I could sort of tell where intersections were, so I was semi comfortable with them.. but regular curves in the road were freaky.
Also on the back on the tandem, bumps can be pretty harsh. They can't see them coming.. and get slammed by them pretty harshly.
A big thing to do from the start is for the Captain to communicate everything. Is there someone walking on the side of the road toward you [or away for that matter] alert your stoker to this.. so they are not startled. Call out bumps, timing it so they can react to it. I don't know of any telescoping seat post, that will allow you to skip this. We do use a Tamer 4 pivot posts, that does cut down on what I have to call out. Previously to getting this post.. putting a lot of miles on.. saying bump for every bump.. became so routine, so automatic..that at times I started accidently saying it in the car
seriously.
At interesections don't cut too close the signs or poles.. take it easy downhill speed wise to start. Regardless of how good your relationship is.. you need to earn her trust, in riding this bike..
My wife and I are a great couple.. and do everything together.. and we did real well on the tandem.. but with that said.. we have had bad days...not often.. but it has happened.
good luck..
), lights/horns for safety ! 
)
