love that they both have their distinct character, flaws and all. we know both have very opinionated personalities, though haneol is decidedly the more intense, and unyielding of the two. we see that when he takes his childish revenge on that dude that hurt da-ae, and yet again when he secretly plans to get back against his ex, despite da-ae telling him to let it go.
i think something will happen first before he'd try to consider da-ae's plan.
all that said, i understand what he's trying to say, given all the information they have so far. and he's not the type to sit still-- he'd do something for the sake of it, even when it's ineffective. honestly, the burden now is on da-ae to come up with a better plan by herself to pitch to haneol. bc as it is, even if the ideal scenario is that they plan together, haneol is being uncooperative.