Along with "staying together" as a buddy TEAM, I have found that many divers, both new and experienced, tend to plow through the water as if it were some sort of race.
I enjoy going slow. I find that if you slow down, you will be able to stay together. You will be much less fatigued and you will burn up less air.
Not only that, but most marine life that you might encounter doesn’t really like the large fast moving presence that a diver creates as they plow through the water. If you simply slow down and even hover, especially near coral heads, all sorts of critters will come out to meet you.
Recreational diving is supposed to be a "relaxing" activity, not a race.
Personally, I don’t want to have to race to keep up with a dive buddy...