Jason Robert Brown’s “The Last Five Years,” which opened this evening at Oregon Community Theatre, is a tight, poetic reflection on the challenges of contemporary marriage, disguised as a musical.

Just two characters populate this slick and appealing show, which is directed by Craig Willis. Jamie, played by Ethan Crystal, is a 20-something writer on his way up; Cathy, played by Evynne Hollens, is rather less successful beginning her career as an actress.

In the show, a sung-though musical, they meet, fall in love, marry, and finally break up over the course of five years. The narrative conceit on which all this is hung is that Jamie’s story is told in chronological order; Cathy’s is told backwards, starting with the splitup. The only time the two characters actually meet on stage in this 90-minute single-act show is at their wedding.

This mostly works. Hollens is sweet and sympathetic as the wife left behind while her celebrity husband is traveling on book tours; Crystal, a newcomer to OCT, is sharp as the up and coming author with a wandering eye. So much of the story involves them talking around each other – it’s a show of sung soliloquies – that the occasional duet, like “The Next Ten Minutes,” comes as a relief.

Brown is best known as a composer and lyricist, heavily influenced by Stephen Sondheim. His lyrics are sharp and clever. Unfortunately tonight they sometimes got lost in the sound mix.

Scenic designer Jeffrey Cook created a clean abstract set – it looks a bit like the set for a ’60s television show – that’s almost as good as the music, which is performed here by an ensemble of six upstage.

“The Last Five Years” runs through February 6. Tickets at OCTheatre.org.