I don't have any guilt or shame either. Guilt is mainly for guys that are cheating, and if they don't want to feel guilty, they can stop cheating or else get a divorce and just live single and clean. Shame I think stems from being judgmental about one's actions, if we are to apply any logic it to it. Lose the judgments and you lose the shame. If you have healthy and fresh thoughts and attitude about your actions, these emotions do not come into play. They only come into play if you allow judgmental thinking to creep into your brain, or even to take it over. I see this in those who have had a religious upbringing that some part of their brain stubbornly clings to, even when battered with logic rebutting those religious judgments.
I have a theory that a certain percentage of men are just not built for marriage, including some friends of mine, but family/societal pressures, and ego, drive them into the institution. It complicates their lives and their true desires, making it difficult to pursue the avocation of exploring other women. They envy people like me who remained single knowing it meant this kind of freedom. That's really what it is all about, personal freedom. But as far as I can see my friends have zero issues with guilt and shame. They know that they are not built as monogamous men, and don't see any need to fight that realization.
Other guys stubbornly cling to notions that they should have a monogamous relationship even when they have failed at it or that it hasn't removed the wandering of their eyes. Ultimately it's up to all of us to figure out what we want and what makes us happy. Some know, but stay in denial, for reasons that cannot be explained. In some, I think they stay in denial because shame is a way to indulge self-loathing, and self-loathing can occur for a whole host of reasons outside the ones discussed in this thread.
I should note that I am viewing this thread as a plea for amateur psychoanalysis from board members in lieu of serious mental health treatment. I presume that if the thread starter believed he had a serious mental health issue requiring treatment, he would seek it and not be here.