Happiness and Truth (in its material/empirical form) do not often co-exist. There is a lot of validity in the maxim "ignorance is bliss". In the realm of metaphysics it is awefully easy to have conflicting views, as most assertions in metaphysics aren't empirically demonstrable. They are by neccessity based from axioms in other words the entire thought process is stemmed from a presupposed assertion. These processes are often entirely logical given that the presupposition is accurate.
Logic is a system that can be applied to any thought process and stemming from a presupposition/axiom. Non-material traditions have flawless internal logic given the presuppositions from whence they stem. This may seem to be an argument that truth is unobtainable because anyone can make a presupposition and build a logical argument from it, however, it is not that. Logic and Happiness can co-exist easily if one does not automatically accept the current popular hypothetico-deductible materialist axiom. If one assumes a different starting point than 'life is short brutish and ugly' because the material logic makes me thinks so then one may very well be happy and completely rational/logical.