Ginny, we got our tandem for the same reason; my wife and I love to ride, but I'm the one guilty of speeding ahead. It's as awesome as you think; we can have a great ride, and still be together. In fact, we love it so much we're going on our first tandem tour sometime this summer!
Riding a tandem is very different from riding two bikes; you do need a lot of verbal communication, and you'll also need a sense of humor, especially at first. On our first ride, we didn't manage to work as a team until 15 miles had gone by; sometimes, I felt like I was dragging her behind me! Fortunately, I had prepared mentally for this (and I'm a pretty mellow guy, anyway), but I can understand how a lot of couples put 10 miles on it and give up.
But once we got the kinks worked out, we flew, and we had such a great time.
If you haven't looked at them yet,
SB's tandem articles are a must-read, and there are plenty of other resources floating around.