UNITED STATES OF TARA. 10:30 tonight, Showtime.

JOHN CORBETT seems to have a way with women on the edge, whether it's the edge of fashion or the edge of insanity.

After stints as the too-good-to-be-true fiancés in "My Big Fat Greek Wedding" and "Sex and the City," he's spent two seasons as Max, the infinitely patient husband of Tara Gregson (Toni Collette), whose multiple personalities - or "alters" - are the title characters in Showtime's "The United States of Tara."

But as "Tara" heads into its second-season finale tonight, Max's halo has slipped, coincidentally just as Corbett's old "Sex and the City" character popped up in a movie sequel that had Aidan, too, behaving less than perfectly.

Even Corbett was surprised when Max sought out Pammy (Joey Lauren Adams), the woman his wife - or his wife's male alter, Buck - had had an affair with, and slept with her himself.

"I was pretty shocked when they let it go as far" as having Max cheat, Corbett said in a phone interview Friday.

"I liked it that Max frayed around the edges," he said.

"It's a treat to be on a show that's such a top-shelf project . . . but, you know, you want to shake it up a little bit now and then. You want to punch a guy and get tossed in jail. You want to just cheat on your wife now and then," he said, laughing.

And it's not as if Tara hadn't been out and about, he said, bringing up a scene in which she'd estimated her personalities had slept with 30 people during the course of the marriage.

"Max has had to watch 30 dudes over 18 years. Maybe he didn't know about them, though," he said.

Working with Collette, it seems, isn't nearly so complicated. "Toni just slips into these characters. You know, that was a concern of mine - how was Toni going to work? What's her process?" he said.

"Part you feels like, 'Oh, man, she's got such a heavy workload here, to be these characters that she's going to need to have her own space and stay in this character all day and won't be able to joke around in between takes.' You know, basically all the things that I like to do," he said.

But "as soon as they say cut, she's laughing and she's back to her Australian accent and that's such a blessing for all of us. Because that kind of acting, for me, gets pretty thin, you know, when you have to sort of tiptoe around it all day long."

Collette, he said, doesn't even mind the Flip Video camera he sometimes points at her during scenes.

"I've done it since my 'Northern Exposure' days. I've filmed everything," Corbett said. Back then, "I had a big shoulder thing I used to carry around."

Among Tara's alters, Buck is his favorite - "he's an affable sort of redneck" - and the newest, 5-year-old "Chicken," his least. "I don't like kids [he laughs]. We have two teenagers on the show and that's great. But I don't have tolerance for little kids and their little questions. . . . That's going to read real funny. My laugh won't be in there at all," he said (yes, still laughing).

As for Buck's recent attack on Max (Tara might've forgiven him for straying, but Buck was incensed he'd slept with Pammy), "Toni throws a punch better than a lot of guys I've been in movies with," Corbett said.

"She had to punch me in the face 50 times that day. Never connected once. I was absolutely sure I was going to lose a tooth in that scene," he said.

"Watch it back sometime. She really winds up and lets that thing go."

'Lie to Me'

Fox's "Lie to Me" (8 tonight, Channel 29) returns, after a long break, with an episode in which Jason Dohring plays a psychology graduate student who matches wits with Tim Roth's Dr. Cal Lightman.

Dohring, who may be the player I miss most from "Veronica Mars," is always fun, particularly in roles that require a boyish but creepy charm. If "Moonlight" had been about his vampire instead of Alex O'Loughlin's, I might have liked it more.

Those, by the way, who miss the show CBS actually made can find "Moonlight" reruns on the CW at 9 p.m. Thursdays this summer, paired with "The Vampire Diaries."

'Smash His Camera'

Speaking of creepy charm, in the documentary "Smash His Camera" (9 tonight), HBO takes a mostly affectionate look at paparazzo Ron Galella, whose long- and short-lens pursuit of Jacqueline Kennedy Onassis landed him in court more than once but whose photographs helped shape the way we remember her (and many other famous faces).

Friends and foes of Galella debate his methods and the artistic merits of his photography, and viewers may, too. The work, which has found its way into several coffee-table books and dozens of museum and gallery shows, makes its own argument.

Do Galella's ends justify his means? Depends, I suppose, on whether the eye belongs to the beholder or the hunted. *

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