Some personal truths can change or evolve but they do not have to apply to everyone.
I would agree that there is an element to morality that depends on the individual and her/his situation. There are three parts to morality. There is the intent of an action, the subjective situation, and the universal natural law. An action has to be good in all three areas for an action to be good. For example, I can do an action that is good according to the subjective situation and the natural law but with a bad intention, the act would be immoral. It seems to me that you are making all of morality fit into the subjective situation and the intention but your leaving out the universal natural law.
Natural universal Law is the one that trips everyone up. Though it is easy for one to recognize what a creator has created something for, many people tend to place an opinion on what is Natural as “good” or “right” and what is Unnatural as “wrong” or “bad”. The first thing I would suggest to someone, is to get out from under these judgments. Nature, by design, does not judge, it just has a responsibility to perform. Humans can hack some Natural Laws (we’re getting quite good at it). But instead of realizing that some Natural Laws inherently give room for such tampering and experimenting, some people feel that this is wrong and feelings are indeed subjective.
I agree that nature does not judge but there sure are consequence if you break natural law. You really can’t break natural law, you just end up breaking yourself on it. But there is room for our behavior because life is not all black and white.
Let me give an example using the three areas of morality that I gave in my past post. Lets say that someone breaks into my home and tries to hurt my children and wife. The natural law says that it is wrong to murder someone. It is also wrong to have the intent to do someone harm. But there is the subjective situation. In this situation it would be good to defend my wife and children. My intent is really not to hurt the person but my intention is to protect my family. If I end up killing the man who is trying to hurt my family, due to the principle of double effect, I would not be breaking the natural law. I did not murder the man; he died as a result of my defense of my family. I agree that this gets complicate but it is necessary when trying to be moral. Sometimes we are really unable to see the ultimate right path and we just have to choose the best we can.
Now if we say, “to hell with the natural law” you end up with a blob of a moral system. It would be like a human body without bones. There is nothing solid to support justice and goodness. The options are not an all rigid system, which your suggesting natural law is, verses a all subjective blob of a system with nothing solid to support anything. The human body has bones to support but there are also joints that allow the system flexibility. The same is true with morality. Because of this there is room for experimentation at times.
An important question that show the problem with the relative moral system was in my last post. Without an objective natural law, what high ground do you have to tell someone that they are being immoral? What Martin Luther King Jr. did for the U.S. would not have been possible without him pointing to the natural law. Or does might make right. Meaning the powerful get to determine what is right and wrong.