Something that you hate about one of your friends?

My bestfriend and i just vc everyday for a long time, it's never boring we both always have something to laugh to or something to say, but sometimes he just mute and disappear for like hours sometimes without telling me anything about what he's doing and it just bother me so so bad, i really get mad sometimes and idk how to react now when he just quits for a bit since i don't really have other friends than him to vc or play games idkk