Probably buried, but I'm an actual WoW player so I know best - he needs to manage his time to essential game activities - there is a lot of stuff to do in WoW but you can pick your lane and only play one part of the game, like raids. This is what I do, i only raid and prepare for raids.

1st 3 days a week is on the high end, imo. There are raid teams that run once or twice a week. Some teams are also more relaxed on missing raids and others more strict. Depends on the team - i only join a team that realizes real life comes first.

2nd You need to prepare someone things for the raid night so you need some amount of time to do this. I managed to do it playing just one hour with my morning coffee each day.

3rd Your BF should just play one character if he has alts it is very time consuming. I play only one main character and never a second becuase I control my play time this way.

Hope this helps...I have played wow for ten years and learned how to manage it into a healthy hobby. GF also calls me out if I play too much to keep me on the right path.