Thesudden engagementofAaron RodgersandShailene Woodleyhas surprised everyone close to them, including people who say that they never imagined the 37-year-old Green Bay Packers quarterback would fall head over heels so quickly.

“This isn’t like Aaron at all,” says a source close to Rodgers. “He’s usually so methodical about everything. I’m not saying he’s not a romantic, but he thinks things through. He’s analytical. He is very careful. He didn’t seem to be the type to get so serious after just a few months of dating, especially after the way things ended with Danica Patrick.”

Though Woodley and Rodgers started spending a lot of time together over the summer, even those close to the couple were shocked when the athlete announced his engagement whileaccepting the NFL MVP awardon February 6.

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“It was so fast that at first, we thought she was just a rebound,” says the source close to Rodgers. “There was no way this could be so serious. Everyone thought it was a casual thing because that’s what he was telling everyone, even when it was clearly not a casual thing.”

Aaron Rodgers & Shailene Woodley’s ‘Surprise’ Engagement Shows How ‘Special’ Relationship Is: Source

For now, the couple has not given friends any details about their upcoming wedding. “It’s a total whirlwind romance. … No one has gotten a ‘save the date’ card yet,” says the insider. “I’m sure they’ll make plans, but they’re really being quiet about it for right now. That’s why this is such a surprise to everyone.”

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But the source tells PEOPLE that there’s no mistaking the joy that Woodley brings Rodgers.

“He’s acting very happy,” says the source. “They’re very content and peaceful. It’s nice to see.”

source: people.com