In an adventurous spirit, Harlequin Dinner Theater swerves from a menu of every-song-a-Cole-Porter-gem to a less familiar but charmingly integrated musical, "She Loves Me." Its score by jerry Bock and Sheldon Harnick was written between their smashes, "Fiorello" and "Fiddler on the Roof."

"She Loves Me" also is innovative. Each song is intergral to the action and fitted tightly into Joe Masteroff's book, which stemmed from Ernst Lubitch's "The Shop Around the Corner," the film that starred Margaret Sullavan and James Stewart. The setting is Budapest in the early, still untroubled '30s, and the mood is one of tender perceptions.

Maraczek's perfume shop can scarcely afford another clerk; but when Amelia deftly sells a music box at her self-arraned tryout, she is hired. Nowack, the chief clerk, has been too courteous to the owner's wife, thereby incurring his jealousy. He also is disliked by newcomer Amelia on sight. It develops that two of these three have been exchanging love letters without ever meeting or knowing the other's identity.

The romantic tangel progresses through a flow of 23 songs of subtle finish. Ever since creating the role of Amelia, Barbara Cook has kept "Ice Cream" and "Dear Friend" on her programs; and besides the title numbr there also are, "I Don't Know His Name," "Days Gone By" and "The 12 Days of Christmas."

James M. Fouchard's blue, rococo Parfumerie folds and unfolds with pleasing proportion to the small stage; and Herlequin's musical director, Hampton King, obviously treasures the delicate score, for which there are eight musicians (live).

The cast is its best in the smaller roles, Brian Donnelly's deft Arpad, Rick Ellis' Kodaly (who sings "Grand Knowing You" with nice bite), Buddy Piccolino's Sipos and Micele Sommer's Ritter (who sings of "A Trip to the Library"). Because Amelia and Nowack are supposed to be shy, repressed types, Patricia Pearce (who alternates with Virginia Craig) and John Combs have trouble making them arresting people, which somehow they have to be to hold our interest.

(The wigmakers have not been doing right by the women lately. THe Pearce wig adds 20 years to her face, and in the Folger's "Two Gentlemen of Verona" both Julia and Silvia are ill-served.)

Since its 301 New York performances of 1963, "She Loves Me" has become a cult favorite through the original cast recording. Harlequin's revival suggests its gentle, treasurable warmth.