Sentence:  This included Mamma , jolly , generous , and pretty , with whom they all fell in love , just as Papa had first fallen in love with her Mamma before he chose her ; and when a young man like Morris Jastrow had enjoyed the Szold hospitality , he felt obliged to send his respects and his gifts not merely to Henrietta , in whom he <WSD>was</WSD> really interested , but to all the Szold girls and Mamma . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)