Paul McCartney has to be an incorrigible optimist. Nearly four years after a bitter divorce and an acrimonious legal battle over money with second wife Heather Mills,the Beatles singer is set to tie the knot once again. He recently proposed to his New York businesswoman girlfriend,Nancy Shevell. The 68-year-old singer and his 51-year-old fiancee started dating soon after his split with Mills. They were often spotted at celebrity events as well as on McCartneys tours. Most recently,they walked the red carpet at the annual Costume Institute Gala of New Yorks Metropolitan Museum of Art. American celebrity magazine US Weekly reported on Friday that the Cant Buy Me Love singer popped the question last weekend during a romantic candlelit dinner for two. People magazine said McCartney had given Shevell a ring,although she did not appear to be wearing it at the Museum event. About a year after separating from Mills in 2006,McCartney reportedly met and began dating Shevell,who sits on the board of New Yorks transportation authority. Famously tightlipped about his personal life,McCartney said in 2008 of their relationship,I just like being in love.