Despite its title, Jason Robert Browns musical chronicles the entire five years of one couples relationship, from the coy beginning to the happy marriage to the bitter end. Jamie (Jason Kappus), just out of college, is a rising star in the literary world, while Catherine (Jessica Skerritt) is an aspiring actor whose success only reaches repertory theater in Ohio. The story is not an unconventional one, but Brown sets the show in motion with Jamie moving forward in time as Catherine moves backward. Not until the end do we really understand their meeting and, more significant, their parting. The Last Five Years is worth seeing mostly for Browns unique score, delivered capably; though both singers are less successful in their upper ranges than in their lower, they fit the roles quite well. (In fact, they bear a striking resemblance to the actors in the New York production, Norbert Leo Butz and Sherie Rene Scott.) Musical director and pianist Mark Rabe is given prominent placement on the stage, and the rare moments in which Jamie and Catherine engage him in the action are some of the funniest in the show. BRENT ARONOWITZ Presented by ReAct Theatre. 8 p.m. Fri.-Sat. 2 p.m. Sun. Ends Oct. 10. The show will be remounted at Broadway Performance Hall, Nov. 1-9.