The decline of Whitney Houston’s career has run in rough parallel to her marriage to New Edition castoff Bobby Brown — every year, she seems to spend less time on her music. On 1998’s My Love Is Your Love, she somehow managed to milk bravado-filled, manic greatness from her firestorm relationship. But Just Whitney lacks any fire whatsoever. Both “Dear John Letter” and “Unashamed” could have been the songs on which Houston bit back with ferocity, but instead she plays it timid. The dance-floor numbers — “Whatchulookinat” and “One of Those Days” — are creaky and unconvincing. Most disappointing is her rendition of the lounge standard “You Light Up My Life.” With “I Will Always Love You,” Houston showed she could take a classic song and make it all her own; this cover, though, only shows an artist vainly trying to reach for what her future once could have been.