I choose not to reproduce. That doesn't mean I choose not to wear a condom. Nature doesn't account for that. In essence, I am using deception to satiate nature's demands without actually impregnating anyone. If I chose to deny my sexuality I might very well find myself staring at that pistol--or developing horrific sexual perversions. The sexually repressed are the most disturbed and deviant of us all.
How exactly is one supposed to live in accordance with these views? You may call me a nihilist for simplicity's sake, but be aware that I make no attempt to live within the boundaries of a predefined philosophy. "Nihilism" =/= depression. My existence is exceedingly brief. The things I do lack meaning. Therefore I put my best effort forth to experience and enjoy as much as possible without getting hung up on fabricated concepts of duty, honor, territory, guilt or shame. I have personal goals, the most significant of which being the pursuit of knowledge. I have hopes and desires. I experience love, anger, hate, joy. These things seem important to me. Yet I am still just an insignificant human. What seems significant to me is no more important than what seems significant to a termite. Life's purpose remains unaltered despite the feelings, goals, hopes and dreams of a species that amounts to little more than dust.