For a while he'd liked Natasha. She was exciting and mysterious and so very haunted by her past. He'd seen their parallels from a mile off, which was reason he'd chosen to spare her in the first place. But he got enough danger and mystery from his job, never mind his love life and so she settled into sister-friend kind of position and they'd never done anything that usually had the connotations of a romantic relationship outside of a mission.
He hadn't expected to find someone else he'd liked as much ever again - hawks were supposed to fly free.
But they could maybe make exceptions for Mockingbirds.