Good relationship skills may be able to influence or persuade, we cannot make someone think what we want them to think. They have to make their own decisions, just as we do. Therefore, having said all we want to say, sometimes it may be best to simply agree to disagree and move on.
Good relationships and productive interactions should include two generally assertive people. Specific situations, however, may require more of a passive or aggressive approach. (If we have no real stake in the outcome, it’s OK to stay quiet; and sometimes the actions of others may cause us to lose some respect for them.)