This is a group based game. I suggest you get used to it.

There are a lot of options for leveling, and it was known to everyone that the first class for many to 50 will be the fastest to level thx to main story missions. Your next few classes will be noticeably slower to level without the main story quest supplementing it. If you get burned out on leveling battle classes try the crafting and gathering classes which can be just as fulfilling.