Ashlee Simpson, 31, and Evan Ross, 27, may be gearing up to celebrate their daughter Jagger Snow's first birthday this week, but their almost two-year marriage is anything but solid.

During his mother Diana Ross' concert at the Hollywood Bowl in LA on July 15, things got extremely heated between the couple.

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“They were bickering nonstop throughout the performance," an eyewitness tells Life & Style, adding that the duo were seated in a box near the stage.

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And before the show had even concluded, “They left in a huff with a fuming Evan striding 10 steps ahead of Ashlee. There’s definitely trouble in the marriage.”

We hope for the sake of their daughter and Ashlee's seven-year-old son Bronx that they can work through their issues!

For more updates on your favorite celebs, pick up the latest issue of Life & Style, on newsstands now! And scroll through the gallery below to see how Ashlee has changed over the years.