It's wrong to assume things about others.
Bill notices that a friend who once struggled with substance abuse is looking extremely run down and behaving strangely.
Bill wants to be there to help his friend.
Bill approaches his friend sincerely and asks what has been going on.
Bill assumes his friend is getting back into drugs and offers up some advice.
Bill's friend confides in him about his depression and appreciates his support.
Bill's friend is offended that he jumped to that conclusion.