Cheryl Rosner, who successfully turned around TicketsNow and spearheaded its sale to Ticketmaster for $265 million, this week left online retail deals Web site...

Cheryl Rosner, who successfully turned around TicketsNow and spearheaded its sale to Ticketmaster for $265 million, this week left online retail deals Web site BuyWithMe.com, her first CEO job since leaving TicketsNow.

Rosner was named CEO of the site in April of this year, and according to the Web sites All Things Digital and BusinessInsider.com, her departure was “mutually decided” by her and the company. At the time of her hiring, BuyWithMe founder Andrew Moss said Rosner was the “right person to accelerate the company’s growth.” BuyWithMe competes with Groupon, which dominates the community shopping and discount Web site space.

BuyWithMe tapped Rosner to head up the company’s “aggressive plans” for growth and expansion, which included adding more cities for which the site offers retail deals. Within months of Rosner’s hiring, BuyWithMe secured about $16 million in venture funding, bringing the company’s total fund-raising efforts to more than $21 million.

But, according to online tracking site Compete.com, since Rosner joined the site it continued to lag far behind Groupon and competing site LivingSocial.com. For example, Compete.com said that BuyWithMe’s unique visitors totaled about 330,000 in November, while Groupon’s unique visitors totaled nearly 11.2 million during the same period. LivingSocial’s unique visitors reached almost 7.2 million last month.

Among the recent coups Groupon recently landed include an arrangement to sell Washington Wizards tickets at a discount.

While at TicketsNow, Rosner helped cement the deal with Ticketmaster, but the company also shed several key executives and laid off dozens of employees.

After leaving TicketsNow, but before joining BuyWithMe, Rosner was appointed to the Board of Directors at e-commerce company Digital River.

At BuyWithMe, Rosner will be replaced by former chief product officer David Wolfe, who joined the company at roughly the same time as Roster.