I kinda know where you're coming from. I got bored of having sex with my wife. I don't know why. She was beautiful and intelligent and I loved her, but soon as we tied the knot, a switch got flicked in my silly little head and I lost all interest in her. Left her within 12 months. I'm not proud of that, but it happened.
That was twelve years ago or so. Not had sex since. Haha.