Your number one, a title Dabi was proud of owning but hated at the same time. Thinking he was just an option for you didn't sit well with him, never has. Yet he wasn't able to muster up the actual words to confess.

And he's good at playing pretend when you're together, but not when you joke about him falling for you.

"Nah, you're just an easy lay, nothing more than that." Dabi lied instinctively. Because he, in fact, was already head over heels for you.