The best description of a tandem bike
I’d read that wherever your relationship is going a tandem bike will get it there faster.
Here’s a recent Craigslist posting supporting that statement:

If the text isn’t readable, here’s the link and the body reprinted below:
For sale is my 1989 vintage argument machine. I bought it sight unseen from some guy in Battle Creek, MI and then paid $150 to have it shipped across the country. It is too small for me, but the size of the arguments it has caused is just right.
Are you going too fast? Too slow? Is the ride too bumpy? Did you hit the brakes without telling anyone? Are you too tall and ruining the view? Is this route stupid and now your partner just wants to go home? Get the answer to questions just like these and hundreds of others with this classic Cannondale Tandem. Have every move scrutinized. Hear every muttered curse that would normally be out of earshot if you took two bikes. Constantly accuse each other of sandbagging with this beautiful bright red argument machine. It’ll make every ride a chore, but at least when you ride a tandem you won’t leave your wife half a mile behind you on the trail because she rides so goddamn slowly.
Comes with free luggage rack.
