Sometimes it takes a whole movie to get to a wonderful last line. But for that last line to truly be wonderful, the whole movie before it has a job to do. So it’s a pleasure to report that actor-turned-filmmaker Matthew Shear, with his debut feature “Fantasy Life,” shows a facility for finessing a meal that lands the last bite. A modest yet amusingly spiky round trip from Manhattan to Martha’s Vineyard, it has the trappings of a rom-com but a trickier soulfulness about its unlikely connection. Shear, with a resting face that seems halfway to panic attack, plays Sam, whose free-floating anxiety is enough to make him faint in public after getting laid off. He also gets squeamish confessing his darkest self-hating thoughts to his avuncular, heard-it-all psychoanalyst (a perfect Judd Hirsch). When an offer from his shrink’s wife (Andrea Martin) to babysit their three granddaughters elicits an impulsive yes — “We know your parents,” she says cheerily to Sam, pushing aside any nagging ethical quandaries — Sam finds himself in the fancy brownstone …