Confusion..

What is it with people in the world. I know that God gave us opertunities so that we may grow as a person and learn new things. I feel the only things i have learned is not to trust others. Why is it so hard to keep up friendships? I have no problem at all doing it, its the other person. Am I the weird one that want's to keep in contact with people while most people can't be bothered?

So here's the deal,

Recently i went on a trip and was able to see some good friends of mine. They are strong Christians and followers of God.  Now they have a son my age and we used to be really good friends then one day it just stopped and now we aren't even friends. I was hoping that when I saw them I would be able to possibly mend the relationship. He has a older sister and i am also very close with her as well. So we got to talking and I told her the whole story about what had happened and she told me some things about how he had felt bad about doing things. (the time before this when we came to visit he totally disappeared the whole time). And it made me feel better, knowing that he did care. When i saw him he acted like nothing was wrong like we were still close friends.  Thing is, i don't trust people easily, and when i do if u just disapear  then we are done. Unless u have like a super good reason. So i had no idea what to do.  Now that I am back I sent him a message saying hi and asking how his trip was (cause he went on one), and he didnt answer me. He always answers everyone.  Now i also tried to contact his sister because we are really good friends and she hasnt answered me either? Yet while i was with her she wouldn't get off her phone. Why would they do this? I told her a lot and she has just ignored me....its really hard for me to deal with this.  

Now i am not asking because i like the guy its just part of the story we live really far away and would never have any sort of relationship other then a friendship.  Its hard because when i see them they are always so nice but i never talk to them until I see them again and that is like every 2 years. 

What do you think??