Barack Obama opens up about his 8 years in office in an upcoming memoir called “A Promised Land.” He reveals that his presidency caused a strain on his marriage with Michelle Obama.Obama says he could sense an “undercurrent of tension in her, subtle but constant,”…”It was as if, confined as we were within the walls of the White House, all her previous sources of frustration became more concentrated, more vivid, whether it was my round the clock absorption with work, or the way politics exposed our family to scrutiny and attacks, or the tendency of even friends and family members to treat her role as secondary in importance.”The former President’s book comes out next week and he will also talk about his historic 2008 election, racism, and Donald Trump.