>>35371380I didn't want the OP to be flooded with my fanfic but this is what I think.
Personally, I believe they had a platonic relationship beforehand. She respected him as her former teacher, she was his favourite former student, etc. He felt bad that Mr. Ketchum dropped off the face of the earth and wanted to help Delia out of the kindness of his own heart (he was also probably pretty lonely). They bonded over the passing of Gary's parents and Delia getting over her denial about her husband returning. They took respective parental roles in each kid's life (Oak- Ash's father figure, Delia- Gary's mother figure). After Ash and Gary left they realized they didn't have to spend as much time together (Christmases, trips to the movies, daily play dates, vacations, etc) but they find out they really miss each other and their get togethers weren't totally just for the kids. It's romantic now but they're keeping it on the down low, the women of Pallet Town love to gossip. Gary probably became aware of what's going on and that's why he's nicer to Ash. Ash is clueless and Delia and Oak are planning to tell him when he's older (which will never happen).
