I swear that questions like this show how screwed up our cultures are. You set boundaries or people walk all over you. Some people are not self aware enough to realize that they are babbling on about a topic people are not interested in. You have to be blunt with these people. If you aren't then you can't be angry with them because you are not saying this behavior is not acceptable. Its my job to set parameters for what is acceptable for people that I have a relationship with. It's there choice to respect that. If they don't I need to make a choice about them being in my life. Its may not be easy to do but its simple.