Mickey Rooney is not the easiest man in the world to be married to.

Ample testimony to that effect, implicit and vocal, has come from his first seven wives. The cherubic, 58-year-old Rooney has thought about the problem. "There's a child in me that's being a man," is his murky explanation, "and there's a man in me that's being a child. I was old before my time, and I've fallen into traps. I'm hard to live with."

Support for Mickey's conclusion is provided by Mrs. Rooney VIII, otherwise known as country singer Jan Chamberlin. She says of her husband of 10 months, "He treats me extremely hard and I rebel. I don't think any of his other wives ever rebelled except Ava Gardner. My heart goes out to him, though. Being married to Mickey is like a game of chess. I'm not sure who will win. It'll probably be a stalemate."

Chamberlin, 40, did not enter marriage unprepared. Before the wedding she researched her predecessors. (See captions, below left, for her judgments.) "Mickey just married all of his girlfriends," she shrugs. Rooney will say little of his wives except "I grew up at a time that when you kissed a girl you had to marry her," and adds, "Jan is smart enough to know that what you see with me is what you get."

One reason Mickey has been such poor husband material is that he's so driven. Right now he's rehearsing a burlesque-type musical, Sugar Babies, which after opening in San Francisco May 8 is slated to hit New York in the fall (as Mickey's first Broadway show). He's also writing several screenplays.

Among his other projects are an advertising business, a commemorative coin operation and mail-order courses in acting and assertiveness training, with a restaurant and a senior citizens' club in the works. He has written a how-to book on successful marriage, which is not to be confused with his novel, The Book Nobody Should Read, both unpublished. He also bets on the horses. His bride says, "He has no understanding of money. His mother used to take care of it for him. Now his accountant does." Jan also says Mickey's pace exhausts her: "I used to fall asleep in the ladies' room at the racetrack. I'd pretend to love it. Now I stay home and putter or lie in the sun."

By his own admission, Rooney is as obstreperous as when he first toddled onstage at 15 months and upstaged two adult vaudevillians. "I detonate at the slightest thing," he says. "But you can't change somebody."

Instead of trying, Chamberlin concentrates on her career, singing at a seedy club near the Rooneys' San Fernando Valley home. Jan, who performs as "J. D. Chamberlin," has turned down Vegas dates while smoothing the rough edges of her act for Tahoe this summer. Rooney sneers at Jan's "so-called career," mostly on the grounds of mismanagement. "I think I could handle her a lot better," he says. "But she told me to stay out of it, and I will."

Born Joe Yule Jr. in Brooklyn to the vaudeville team of Joe Yule and Nell Carter, Mickey hit the sawdust trail at the age of 11 days. At 3 he had his own doll-size tux, and at 7 was supporting his divorced mom in Hollywood by filming Mickey McGuire two-reelers at $200 per. The fourth of his 15 Andy Hardy movies, Love Finds Andy Hardy, made him a star. In 1940 he was an Oscar nominee at 19 (for Babes in Arms, with Judy Garland) and in 1939 and 1940 he was the biggest box office draw, male or female. Since then he has had more comebacks than a Capistrano swallow. He was in a slump when he met Jan; she talked him out of moving to Florida. He stayed in Hollywood and since 1975 has made seven movies, including the Disney hit Pete's Dragon and Francis Coppola's unreleased The Black Stallion.

Daughter of an Air Force colonel, Jan grew up in Los Angeles and studied psychology in junior college. But she married script supervisor and actor Lynn Aber at 18, and had two sons while odd-jobbing. A church choir member since childhood, she took singing more seriously when she and her husband split after eight years. Now she studies voice and has been laboriously cutting her first C & W album in a Houston studio for 15 months.

She and Rooney met at a 1974 L.A. party; she arrived on the arm of country musician Mickey Rooney Jr., 33, oldest of Mickey Sr.'s nine children. "I was working on some songs with Mickey Jr., and he wanted me to drop him off," Jan recalls. She and Mickey Sr. were not exactly a chemical reaction. There were differences in age (18 years) and height (his 5'3" to her 5'6"). But Mickey Sr.'s jazz piano captivated Jan. They lived together for three years while she demurred about marriage. (He publicly insists they've been married since 1976, but Chamberlin shrugs: "Mickey is a moralist.") After she said yes, they bungled the ceremony five times. "We kept forgetting some important document or other," she remembers. On the real wedding day Mickey drove to the church with friends, forgetting Jan at home.

Now the Rooneys live in a three-bedroom house with her sons Chris, 20, and Mark, 17, who are fond of their stepfather despite his no-drugs, no-liquor rules. (Rooney neither smokes nor drinks.) "It's been fun," says Chris. "He's been really strict with us, but it's for the good. We were both troublemakers when Mom met Mickey." Their favorite film (from the Rooney library in the basement) is Boys Town.

In the kitchen Jan survives on blended juices, while self-proclaimed gourmet Rooney eats "everything." "He grabs the utensils from me," says Jan. "He always says I'm not putting enough of this or that in it."

Their problems are not all that light-hearted. "He wants me here at home when he's home, which isn't often," worries Jan. "With an older man you have to make compromises, but you also have to make sure you remain your own person while accommodating." She adds, "Whenever we have fights, he calls my mother to come over and referee. He adores her."

Tentative about romance ("From the moment you say 'I love you,' it almost spells doom"), Rooney ponders his marriage with some satisfaction. "You can't analyze it," he says. "Sometimes it's really good. Sometimes it's really bad. It's consistently inconsistent. It's frustrating and it's comfortable. It's always tough to live together."