Surely it's not too early to feel nostalgic for 1992. After all, it was 16 whole years ago. No iPods yet — and those clunky cell phones! Kurt Cobain was still alive and Bill Clinton hadn't even met Monica Lewinsky, much less have sexual relations with that woman.

Thankfully, writer-director Adam Brooks doesn't wallow too obnoxiously in the not-so-distant kitsch with "Definitely, Maybe," a surprisingly clever romantic comedy that starts brightly but unfortunately loses its spark at the end. He mainly uses the period to establish the story of Ryan Reynolds' Will, a disillusioned New York ad man who's just been served divorce papers when the movie opens.

That afternoon, he picks up his 10-year-old daughter Maya (the always adorable Abigail Breslin) from school and is horrified to discover that she and her classmates have had a sex education lesson, which prompts a flurry of uncomfortable questions about where she came from and who else Will dated besides her mom. (Maya has fun using the new terminology she's learned that day, loudly and often.)

And so Will reluctantly tells her of his romantic past as a bedtime story, changing the names so that she (and we) won't know which girlfriend became her mother until the end. There's Emily (Elizabeth Banks), his wholesome college sweetheart from Wisconsin; April (Isla Fisher), a flighty but quick-witted aide he meets while working on Clinton's presidential campaign; and the sophisticated writer Summer (Rachel Weisz), who's out of his league.

Brooks, who previously co-wrote the flat sequel "Bridget Jones: The Edge of Reason" and the reasonably pleasing "Wimbledon," jumps back and forth between Will's recollections of his various interludes and his present-day attempts to keep them clean for his daughter, who chimes in with sweet and frequently smart-alecky commentary.

His characters are distinctly drawn and well cast, with each woman believably shaping Will into the man he becomes.

And Reynolds, who is in every scene, continues to move beyond such raunchy comedies as "Van Wilder" and "Waiting ..." to establish himself as a viable leading man.

But while Brooks has made an inventive romantic comedy — something that seems impossible to do these days — his ending takes way too long and makes too many twists. We have to slog through repeated permutations of who Maya's mom might have been and who Will's soul mate might be.