sometimes it's because they worry about how the other person will take that.

or because they don't want to burden other people with their problems.

adds or because they don't know how to actually start that kind-of conversation.

or because they don't want to admit that it bothers them - to themself either.

knows she is entirely guilty of doing this. : / (for the reasons above and others)

people should just say what they want

that if something bothers you there is no reason to stay uncomfortable.

agrees with this mostly, but has trouble actually following through on it.