On the historic day this summer that Paul Katami and Jeff Zarrillo were married in Los Angeles and Kristin Perry and Sandy Stier exchanged vows in San Francisco, a similar wedding took place in the backyard of a house in Long Beach, Calif. The third nuptials belonged to fictional characters Stef Foster and Lena Adams of “The Fosters”—TV’s first gay characters to say “I do” since the Su