Jack's a little rough around the edges but warms up throughout the season. The former military man struggles with night terrors and getting close to anyone, which is part of why he's kept Charmaine at arms' length for years.
After he and Charmaine split, he finally lets himself get close to Mel, officially wooing her. Alas, that's when Charmaine drops the bomb that she's pregnant despite never thinking she'd have children. She writes a letter to Jack to tell him, which Hope intercepts. Hope accidentally spills the beans to Mel before Jack can tell her, causing a tiff between them.
Jack tells Mel he's falling in love with her, but she tells him she can't handle him having Charmaine's baby. Though Charmaine tells Mel that she knows Jack feels for her the way he'd never felt for anyone else, Mel still is seemingly ready to walk away, leaving Jack behind.