I think at this point Dabi doesn't really love Doc but he loves the feelings she gave him (Like she's the only person who genuinely tried to help him and listened to him, especially since she's like... a nice and respected person. She didn't have any reason to be nice to someone like him and should've treated him like her colleagues yet she didn't.)
I think if anyone else than doc (with the same status) did treat Dabi the same way he would've also got obsessed over them.
(I mean no disrespect don't take it the wrong way🙏)
This is exactly what the initial draw was — basic kindness and compassion. But Doc made these two traits more complex when she added her personality to the mix. So, he started out fiending for her attention because it’s the closest thing to positive reinforcement he’s ever felt; however, over time, he fell for her humour, her intelligence, her true essence and flavour 🤌