If you want to ride together, I have found its best to have the slower rider setting the pace (on the flat or climbs). If the faster rider wants to pull, then it can also help the faster rider to wear a mirror to see if the slower rider is falling back.

One way of training together is to do circuits on the same course. So lets say you both want to do a 60 mile ride but you both want to do it at your own pace. So pick a route which is 20 miles let say and do 3 laps. Whoever finishes first, does the course in reverse until they meet up with the slower rider. Then you can finish together.

This also works for climbs as well. Instead of waiting at the top, the faster person goes back down and meets up with the slower rider. And then climbs back up and back down until the slower person is done. This way the faster person doesn't have to wait a long time at the top and can get more training in over the same period of time.