The OP is a nihilist, nihilism is a legitimate philosophy. I would recommend he read Jacques Derrida who, IMO, addresses nihilism well in a post modernist society through the deconstruction method. What this does is allows a person to recognize that we will not know the "truth. rather than denying the truth, as the OP is doing on this thread. Really too much to post here, but in a nutshell the individual should free himself from expectation, develop your own 'truth' but understand that any 'truth' you develop is really only assumption, and could be wrong. It's really Socrates... placed in modern context.
If you believe that nothing you do really matters... well this is based on some level of expectation. There is really nothing you can do about disappointment that things are not going as expected... but you can minimize the negative feeling you have if you free yourself from expectation. Stop thinking "I will do this, than I will get that." Rather believe: "I will do this, than I will see what happens... then I will respond to that reality... etc etc". Just live your life like this and negativity is minimized.
I do agree with the OP that many come here looking for solutions to problems, and when they don't get them they are disappointed. I have said it before, and I will say it again. When it comes to women, nothing you do will guarantee results. And the key to success (well some success, because ALL of us have failure) is to abandon expectation. Be the best version of yourself possible, and make an effort... if it doesn't work out... move on quickly and put the past behind you. If you agonize over the unattainable, you will begin to suffer the negative aspects of nihilism.
I consider myself a nihilist, but I have freed myself from depression by understanding that the only thing that really matters is what is happening right now. The past is irrelevant because you can not change the past: the future is also irrelevant because it hasn't happened yet, and there are no guarantees. It's good to have goals, but do not be married to them.