Breaking up isn't hard to do. For most rock bands it's a way of life. Yet it seems for every farewell there's a reunion, and perhaps no band has been "reunited" more often in recent years than Frankie Valli and the Four Seasons.

As in previous area concerts, Valli and the sextet that currently makes up the Four Seasons had no trouble stirring memories at Wolf Trap last night. With a list of hits that reaches from here to "American Bandstand" and back, the group couldn't help but have a warming effect upon the largely middle-aged crowd that snuggled in the chilly night air.

But to Valli's credit, his show wasn't purely nostalgic. Unlike some of his contemporaries, Valli remains in fine voice, and throughout the night his familiar falsetto soared as surely as ever, sometimes piercing the slightly updated rock accompaniment, sometimes hovering above the doo-wop harmonies that form the basis of the Four Seasons' style.

Valli also doesn't burden listeners with unnecessary sentiment or frivolously contemporary arrangements. The songs -- "Sherry," "Dawn" and numerous others -- were delivered faithfully, with equal measures of sincerity and enthusiasm. That combination triggered countless ovations for both the singer and the band.