Hilary Duff finally decided to Wake Up.

Sources reveal exclusively to Us Weekly what exactly pushed the actress to file for divorce last month from Mike Comrie, following four years of marriage and one very amicable-seeming year of separation.

Duff, 27, filed papers on Feb. 20, one day after the Daily Mail reported about Comrie's behavior during a wild night out at Beverly Hills hot spot Mastro's.

A source confirms the report to Us, saying the former hockey pro was "aggressively hitting on" his waitress at the restaurant. The insider says Comrie was "calling her beautiful, telling her he wanted to take her out."

Comrie's advances, however, were rejected, which prompted him to go "up to another woman," the source says. The father to 2-year-old Luca then "drunkenly threw money at [the other woman] and asked for sex."

A source close to Duff tells Us that Comrie's behavior that night was the final straw. "Hilary finally realized Mike wasn't going to change," the insider explains. "He totally blew it and chose to live life like he was single."

Since the couple separated last January, the two have remained friendly and amicable, even spending Valentine's Day 2014 together. On multiple occasions, Duff discussed their split, revealing during one interview that she was holding out hope.

"I mean, if there wasn't a chance for getting back [together], I think we would've filed for divorce," Duff told The Kyle and Jackie O Show last September.

As for why she waited? Duff explained to Us Weekly last May that they were "not in a rush for anything." She noted: "We are just trying to enjoy our lives and figure out what makes us happy and it's working for us."

For more details on the Duff drama, Brandi Glanville's possible end with the Real Housewives of Beverly Hills, Rihanna's sexy birthday with Leonardo DiCaprio, and Jessica Biel's baby hideaway, watch Us Weekly's Hot Stuff video above, featuring Entertainment Director Ian Drew and "Nobody Love" singer Tori Kelly.