It’s not easy being a girl. And not just because of the acne and the algebra. There’s also the task of monitoring the ever-shifting landscape of teen popularity. (Boy bands? So last Wednesday.) The current object of their collective affection? Orlando Bloom. Most people past puberty haven’t heard of him, but Bloom just made Teen People’s list of ’25 Hottest Stars Under 25,’ and next month he’ll be named one of YM’s ’20 Hottest Guys.’ (Hint: he’s the one running from fans in those ubiquitous Gap ads.) The Brit had only a minor role in ‘The Lord of the Rings,’ as the pale elf with the waist-length blond hair. But somehow girls saw through the Bon Jovi phenomenon, spotting the hottie hiding beneath that coif. Since then Bloom, who seems intent on dodging the teen-idol mantle, has starred in ‘Black Hawk Down,’ and he’s currently filming a Western. ‘Orlando’s a very serious actor, says his publicist. That’s right, he’s not just eye candy. He’s classically trained eye candy.