Loosing friendships because of death???

It's interesting how some people react to death. With some people I have emailed back and forth regularly. Some of them have been real good friends. And when my mom was still in hospital, some of them wrote to encourage me and assured me that they would pray. Then she passed away and... nothing! No reaction at all. No email contact anymore. I mean I understand that people are overwhelmed with the situation and don't know what to write. I'm overwhelmed with the situation, too. But do friendships break because of death in the family??? Because people don't answer to your emails anymore? People that have written so regularly before?! How strange is this?

And others that do answer to some of your emails weeks later don't mention that certain issue at all. It's one of these hot potatoes. I wonder if it is because they don't know what to say or if they don't want to raise the subject because they think I don't want to talk about it or what the heck?

If these people were not close at all, that would make it different. But some of them are real good friends, at least that's what I have thought.
So, now...I guess I should be typical German direct and ask them? Maybe?