I can understand needing a little cool off period before discussing an issue. I am that way, too, but that usually means a long walk in the park, a hard workout in the gym, or something that gives me time to myself for a couple hours.
Disappearing for days without letting you know where he is and completely cutting off contact appears to be: 1. extremely immature and/or 2. an indication of his only coping mechanism of disagreement/anger is running away from it. The fact that he does the same with his family implies that they tolerate this behavior and it is probably been going on for a long time and unlikely that he will change.
One year is not a very long time. If I were you, I would end this relationship and not waste anymore emotional energy on this man, unless you just want a "good time guy" and not someone you can count on. What happens if you were to get married and decide to have kids, and he were to pull one of his disappearing act when you were about to go into labor?
I completely agree with Demontespan. If this happened once, it would be worth it to give him another chance, AFTER you'd had a discussion about it, and informed him that running away from a problem is NOT how it's fixed, and that you will not tolerate that kind of treatment. The second time should have been the last time! It's time to end this relationship because this guy will do this to you forever. If his family tolerated it, then it's been going on for years, and it will never stop. You need to immediately STOP texting him, stop contacting him in any way. And you can be sure when he realizes that you've stopped, he will reappear. He is "punishing" you for his imagined problems, and you're playing right into his mental problems.........by being upset, and desperate to contact him. He's laughing, knowing he has you wrapped around his fingers. He has mental and emotional problems, and you will be the one paying for those problems for the rest of your life unless you get out NOW, and stay out. There is nothing to panic about........he's fine, and he's enjoying the misery he's causing.
Stop contacting him right now........and I can assure you that he's fine, and once he realizes that you're "over it"......he'll be back, When he comes back, you tell him that you are finished, it is over and he can go away and STAY away. He will promise never to do it again, but he WILL do it again, because this is how he is, and he will never change. You have wasted one year of your time with him, now do NOT waste any more of your life on a selfish,unstable, immature and cruel person. You deserve better than that.
PS: Problems are NEVER solved by running away from them. If you can't talk to a person, and work out the problems, they will never go away, and nothing will change or get better.
My exH was one who needed a cooling off period and it took me a while to realize that by pursuing him and trying to talk before he was ready it just made things worse. However, we are talking about a period of hours or maybe one day not disappearing for a week--and the person should tell you "I'm upset right now. I need to be alone tonight but I'll call you tomorrow." This habit of not even being willing to text you back to say that he's ok is unacceptable. What would he do if you were living together? Would he leave the house for a week with you not knowing where he is? He needs to learn how to have a disagreement with someone and handle it in a mature way because when you are living with someone or married and esp. with kids, you can't just disappear on your family whenever you get mad. I agree that its' a way of punishing you because by the time he reappears, then you are probably so relieved that he is ok and talking to you again, that the original problem never gets solved because you are too afraid to bring it up because he might run away again. I think you should not take him back.
Your friend is right, you have to decide whether you are willing to accept his behavior because so far he's not willing to change it. He knows that it is distressing to you and doesn't seem to care that he makes you upset for days on end, it's sounds like a dramatic game to him---and its definitely "all about him" without regard for the people who worry about him. That's not a good way to show that he loves you. I would not tolerate it. I say, end this relationship so you are free to meet a man who shares your values AND cares about your feelings.