What's going on with Sinjin and Rosamond

Sinjin meets Rosamond at the Morton. Sinjin thinks that he made a wrong decision about his career choice, until he a "calling" from God that changed his mind on becoming a missionary. Jane notices that every time Sinjin and her would talk, Rosamond would interrupt their conversation and from that their interctions caused Jane to think that they're in love. During Ch.32, Sinjin finally declares that he is in love with Rosamond and is tempted by her beauty, but he thinks she wouldn't be a great wife for a missionary because of her shallowness, flirtatious, and sillyness.