It was The Joker, surprisingly, who stopped him from breaking his cardinal rule against killing.
"And now you know. I'm not noble," Bruce tells Selina. "I"m just what he made me."
Bruce felt she needed to know before making her decision. Catwoman's response is a lesson on what true love really is (so if you thought you couldn't get deeply important reminders from comic books, you're about to be proven wrong).
Selina goes on to explain that all their sins, "earned tragedies" and pain cannot compare to the love they have for each other.
She asks him to ask her again and, this time, she gives him his long awaited "yes".
USA Today published an interview with writer Tom King ahead of the release which contains some interesting details about the plotline.
"That to me is what true love is," King said in the interview. "It's showing who you truly are to someone. It's letting someone know deep down who you are and that's horribly frightening and it scares Batman as much as anything ever has.
"They're two broken people and because they're broken they have the edges that fit together."
Catwoman's answer is an important development in the plot. As King explains, Batman's 78-year-old character has lived "in every kind of medium humankind can produce".
"But we've finally taken you someplace you haven't seen before, so we're going to explore this," he adds.
As for what is next for Batman and his new fiancee, only time will tell. But King warns that no one in Gotham City will be rushing off to buy wedding gifts because there's a lot to resolve before we even have to start worrying about whether they'll have a Bat-Cat or a Cat-Bat type of baby.