more-kutcher-moore-split.jpgEven after it was announced that Ashton Kutcher cheated on wife Demi Moore with 22-year-old Sara Leal, the couple put on a united front and appeared to be making an effort to save their relationship. However, after two months of trying, Demi announced last week that she was planning on filing for divorce. So what went wrong?

Apparently the happy couple were having major drama, and had been for quite some time. "The fighting could get pretty intense," a source told People. "Whatever counseling they did was fine for a quick fix but could not get to the heart of the problem."

It is also being reported that Demi and Ashton had an open marriage, with several online reports hinting that Demi is bisexual. A source told Star magazine, "Demi is attracted to women just as much as men, so she didnt always get all she needed from Ashton." So what about the other people involved? "Everyone in Hollywood knows about their arrangement, but theyve managed to keep it a secret from the general public," the source continued. "She was cool with Ashton having flirtatious relationships too. Somehow they made it work all these years. Both of them were respectful of each other. It was a lot of fun for them." But when Ashton stepped out with other women, Demi apparently couldn't deal with it.

"The final straw with Sara Leal has just been too humiliating for Demi to get over," a source close to the former couple tells Us Weekly. Ashton allegedly had sex with Sara on the weekend of his wedding anniversary, and Demi "just couldn't look at Ashton the same way and the marriage completely unraveled," the pal added. "She still loves Ashton but feels he went too far and disrespected her and their marriage in a way that can't be taken back. She wants to set an example for her daughters and this was just something she could not rationalize to them or to herself."

"She really tried everything she could to forgive him and accept his apologies," the pal continued. "At the end of the day, the public humiliation and the example she was setting by staying in the marriage just wasn't the right thing for her."