Taylor Lautner Addresses Kristen Stewart's Affair With Rupert Sanders

The "Twilight" cast has said little about Kristen Stewart's affair with married filmmaker Rupert Sanders -- until now.

In the December issue of Cosmopolitan, Stewart's co-star and close pal, Taylor Lautner, 20, is asked to share his thoughts on infidelity. "To be honest, I've never been involved in any of those situations, so I don't know [if trust can be regained]," he says diplomatically. "It would be just a guess and a shot in the dark, and I don't want to give that if I haven't even been there myself."

PHOTOS: Kristen Stewart gets caught cheating on Robert Pattinson

Lautner adds, "Kristen is fantastic at everything she does. I'm always proud of her."

With fellow "Twilight" hunk Robert Pattinson, 26, recently deciding to give his longtime love Stewart, 22, another shot, Lautner says he "absolutely" believes it's possible to reconnect with an ex. "It depends on how long you were with that person. If it was a long, serious relationship, I think it's quite easy to rekindle. I guess it depends on what damage has been done. There's no ex out there who I'm not friends with today, and I'm extremely thankful for that."

PHOTOS: Taylor Lautner through the years

Lautner has been single since splitting with his "Abduction" co-star Lily Collins in September 2011. His previous girlfriends include Los Angeles Clippers cheerleader Sara Hicks, country music star Taylor Swift and former "Wizards of Waverly Place" actress Selena Gomez.

"Honesty and loyalty are key," he says of being in a relationship. "If two people can be honest with each other about everything, that's probably the biggest key to success. I like to think of myself as very loyal, and I love everyone I surround myself with, whether they're friends or girlfriends or whatever. I love people."

PHOTOS: Love lives of 'Breaking Dawn' stars

Even so, Lautner winces at the idea of being set up on a blind date. "I get nervous before everything: dates, filming, awards shows," he tells Cosmopolitan. "It's too awkward for me. I would have to trust the friend who was setting me up, and they would have to highly recommend the girl. I'm picky. Maybe one day."

RELATED ON WONDERWALL & MSN:

Taylor talks about growing up on 'Twilight'

Richest stars under 30

Celeb eye candy