Why the Perry, Brand split shocked friends

"They were very affectionate, always holding hands," a source who knows Katy Perry and Russell Brand said.

STORY HIGHLIGHTS

• "I was shocked when I found out," a source says about Brand and Perry's divorce


• "I thought they would be together for a long time," the source says


• "These aren't people who give up," another source says

() -- When Russell Brand announced on December 30 that , it wasn't just their fans that were caught off guard.

"I was shocked when I found out," a source who knows the couple tells PEOPLE. "I was really surprised that Russell filed for divorce so quickly -- especially at Christmas time."

Continues the source: "I thought they would be together for a long time. Maybe not forever -- but definitely not just 14 months."

"They were always laughing," the source says. "They were very affectionate, always holding hands. They seemed like they were really in love."

Another source who spent time with tells PEOPLE that both of them "took marriage very seriously."

"These aren't people who give up," the second source says. "I always thought they would work on their marriage if they had trouble."

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