Can I be mad at my boyfriend for taking 6 hours to have dinner with friends?
Wow. Why did it take him 6 hours?
His intentional unbalance of priorities is the reason, we want our dinner together.
It's fine to sometimes feel a little mad at your bf if he's spending more time with friends. You should tell him that it makes you upset.
I would just talk about it but I am not sure if he will listen.
You don't get anything if you don't talk about it. Maybe it will help you feel better and he will understand why you feel slighted when he spent more time with his friends.