ON PAPER, YOU WOULD expect Wale to be happy. His last album, 2013’s The Gifted, topped the Billboard 200, and 2011’s Ambition (his first on Rick Ross’ Maybach Music Group imprint under Atlantic after an album on Interscope) hit No. 2. His strong new set, The Album About Nothing, released March 31, is inspired by Seinfeld and features Jerry Seinfeld himself. “We’ll crack on each other,” says Wale, 30, of their relationship. “He’ll talk about the dumb shit that he does, like, ‘I spent the day watching a documentary on making boots.’ I’m like, ‘Bro, really?’ ” But behind the good times, the Washington, D.C., rapper says he’s got issues, and they’re just under the surface on his deceptively titled album: drug and alcohol use, a miscarriage and what he…