pIt's bad enough when your love life is going nowhere fast -- it's worse when everyone else's is soaring pThat's the personal tragedy that appears to have befallen Amy O'Sullivan, asshe careens toward the Big Three-O with what she laughingly refers to as a career at a dead end. Amy's little sister has come home with her Golden Delicious Australian fianc in tow. Amy's girlfriend Beth is also planning on tying the knot with her own Mr. Right in the near future. And another friend has just slept with the man Amy figured she herself might end up marrying So what's a perennial bridesmaid to do . . . after she's spent more than enough time and energy lying in bed, wallowing in self-pityWhy, move on, of course She's needed sort of at the bookstore where, asStory Princess, she's expected to enliven young lives, even as her own sinks deeper in the mire. pThen again, perhaps there are actual Prince Charmings out there in the real world. And a pitiful princess never knows what -- or who -- is