Final answer:
Shirlee and John share companionate love, which consists of intimacy and commitment, but not passion, as described by Sternberg's triangular theory of love.
Step-by-step explanation:
Shirlee and John, being widowed and finding comfort and happiness in each other's company without an active pursuit of romantic passion, share a type of love referred to as companionate love. According to Sternberg's triangular theory of love, companionate love is characterized by intimacy and commitment but lacks passion. This form of love is often seen in close friendships and family relationships, where the deep bond and mutual support are present.