it's more than okay. but in another way you should listen to his side of story , maybe he had works to do all day or he was busy or he had some problems with his family , he maybe has his own strong reasons. but if he don't then it's okay to be mad :)
Only if you make an attempt at talking to him and he flat out ignores you all day. If you expect him to reach out to you and talk to you, and then get mad when he doesn't, you don't have the right to be pissed. Because technically you did the exact same thing as he did, by waiting silently.
No. Happens a lot with us. He has to go to field training for sometimes a week in the middle of nowhere and there's no contact because he has no signal. But I prefer talking daily.