Breakin' All the Rules(2004)

Overview:

After being dumped by his model girlfriend, aspiring writer Quincy Watson quits his job and is inspired to pen the ultimate how-to book on breaking up. When it becomes a smash bestseller, he starts giving his player cousin, Evan, choice tips on how to win the battle of the sexes. But when Evan's beautiful girlfriend Nikki gets wind of the plan, it's these players that end up getting played.