I actually think Wonder Woman is the only woman Batman can have a stable and last relationship with.
She's a hero in her own right, so she'd be understandable about his double life, the dangers his other life poses, his busy schedule, the unpredictable and often canceled dates, and his general sacrifices.
She's superpowered and immortal so there's no risk about her getting crossed in the cross-fire or putting too much damage on her body with age.
She's pretty understandable, calm, and compassionate.
They share a lot in common. From life experiences, to certain world-views, principles, and hobbies.
