Donald Margulies's Pulitzer Prize-winning play, Dinner With Friends, muses on marriage and the substitute families that married people form with other couples. Two people, immersed in their own misery, separate. Their close friends -- a pair of trendy and dedicated foodies -- immediately sense the cracks in their own relationship. The original two move on, but the second two continue to struggle. That's about it for plot, but there's all kinds of resonance here having to do with affection, commitment and the changes brought about by time. The dialogue is evocative and clever, and, under Bruce Sevy's engaging direction, this cast was strong.