President Barack Obama had a cloak of invincibility. Every misstep was excused by the media and most of the nation, from the occasional slip of the tongue - see Henry Louis Gates and Kanye "jackass" West - to larger, unresolved issues such as health care. Now the cloak of invincibility has worn down into shreds, exposing Obama and making him vulnerable, almost human. The honeymoon period that began on that Tuesday night in November is over, and the bitterness of marriage has set in. Obama promised to be that fianc