As it turned out, Simpson's birthday surprise turned out to be a shocker: Although Romo had insisted that things between them were "going good," the Dallas Cowboys quarterback ended their year-and-a-half relationship on July 9 – the night before the singer turned 29.
"She is heartbroken," says a source. "She loves Tony. But it's been difficult lately. He's busy with his career and she's getting ready to shoot her show (The Price of Beauty). They decided to part ways."
But nobody would say that the pair didn't give their relationship a good shot – weathering many a storm and breakup rumors before.
Early RomanceAfter Simpson and her family went to see Romo play for the first time in November 2007, things moved pretty quickly – he even kissed her on their first date!
"The fact that this guy, on our first date, in the first 10 minutes of dinner, wanted to lean over the table and say, 'This is my girl and I want to kiss her' – our first kiss in front of everybody – was awesome," Simpson said at the time.
Days later, they shared Thanksgiving together in Texas – but their first bump in the road came quickly. In December, after Romo played his worst game ever while his new girlfriend looked on from the stands, some fans blamed Simpson for distracting Romo and causing the team to lose.
Still, the couple rebounded with a Mexican getaway, a romantic Valentine's Day dinner and a public PDA session on his birthday (complete with a frosting fight) in April.
United FrontBy May, rumors began to swirl that the couple was heading for a split and that Simpson was devastated to learn her ex-boyfriend, John Mayer, had started dating Jennifer Aniston. But her rep denied talk of a breakup, and Romo escorted Simpson to her sister Ashlee's wedding that same month.
The summer seemed blissful for the couple: Simpson went home with her man to Wisconsin where they had dinner with his parents. Later, she dedicated her song, "You're My Sunday," to Romo during a concert tour for her country album and even gushed to PEOPLE that he was "the love of my life."
At the beginning of 2009, Romo stood by Simpson when she was slammed on blogs for looking heavier, even taking her out for a romantic night out in New York.
"I've never dated a guy that was more simple," she swooned in the May issue of Vanity Fair. "I'm always there for him ... And he knows he has me to come home to."
Quick SplitIn recent weeks, however, the couple have been spending time apart. A source tells PEOPLE: "They've been having a lot of problems lately in general." Their last public appearance together was July 1 when she sang the National Anthem at the National Golf Tournament in Bethesda, Md., and Romo played a practice round with Tiger Woods.
On July 2, Simpson still seemed upbeat and excited for her upcoming birthday. She posted a message on Twitter to her friend Emmy Rossum about her upcoming party: "Can't wait to see your costume on the 10th! Birthday evite coming soon. You are always the best dressed!!!"
But just nine days later, Simpson ended up celebrating her birthday quietly "with family and close friends," according to a source close to Simpson. Meanwhile, Romo was spotted out with a group of friends at L.A. hotspot MyHouse. According to a source, Romo was out with the guys to "lift his spirits." Adds the source: "His friends wanted him to have some fun before football training camp starts."
On Sunday, Simpson again took to Twitter to write this reflective post: "Everyone needs to know that hope floats ... grab the strings and pull it back to you. Falling asleep with my mom and the dogs. Please lord give all of my beautiful fans, friends, enemies, and family rest. Bring all of us peace."
Says the source close to Simpson: "[Jessica and Tony] were good together for along time. But I guess it wasn't meant to be."
Reporting by K.C. BAKER and JENNIFER GARCIA