Friend A was married to Friend B. Now they are divorced and I'm friends with A and B. Can I block friend A from seeing posts friend B tags me in and vice versa?
Facebook provides the following methods which can be used based on your requirements
Blocking particular friend
Timeline review allows you to review the posts from your friend before they appear on your timeline.
It can be found under Settings > Timeline review
It can be activated if you just need to restrict others from tagging you in their posts.
The next option is blocking the particular friend. This will entirely avoid all the activities from your friend.