Milestones

SEEKING DIVORCE. Sylvester Stallone, 41, blood-and-guts, hero-as-underdog actor-producer whose Rocky and Rambo films have grossed more than $1 billion; and Brigitte Nielsen, 24, statuesque (6 ft.) Danish model and actress (Red Sonja, Beverly Hills Cop II); on the ground of irreconcilable differences; after 19 months of marriage; in Los Angeles.