Kris Humphries and Kim Kardashian
11/04/2011 at 04:00 PM EDT
The demise of Kim Kardashian
's 72-day marriage to Kris Humphries stunned the public, but the topic of divorce
had come up before with the pair, who were going through a tense time.
The possibility of divorce had "been on her mind a lot lately," admits a source close to Kardashian. "She was completely torn."
The stresses of settling into newlywed life in the spotlight, their living situation, personality conflicts and filming for her E! reality show all contributed to the mounting tension for the two.
Kardashian, 31, waffled about her decision up until the night before the filing. "Kim decided really last minute," says the source. "It was not an easy decision to make."
The week before the split, Kardashian, who returned Thursday morning to Los Angeles early from a planned trip to Australia, had "talked about the possibility of filing and she told Kris it wasn't going to work," continues the source. "Everything she dreamed of in her mind was right there in front of her but what she realized is that her heart wasn't there."
Humphries, 26, who is with family and friends in Minnesota
, was caught off guard when Kardashian ultimately decided to file Monday. He was "surprised by the timing," says a source. "He found out about the divorce papers via the Internet. He thought they were going through troubling times and a really tough situation but he thought they would figure it out."
The whirlwind romance
didn't leave much time for the couple to spend together before walking down the aisle. "They never took the time to really get to know each other," explains another source. "After they got engaged it was like, 'Let's do this!' "
And the strains of reality television weighed on the pair. "It's too much to have a TV show and be so public," says a source. "The stress of all that really came down on them. Kim learned the hard way she can't have it both ways."