One way I'd like to see a couples relationship to advance is for one of them to coincidentally run into a character in passing that reminds them of their crush and realizing she finds them attractive. Like 'oh, she's pretty, like Takamine... Wait.. 😳" or something.
I think that would go far better to disperse the thought that their feelings are just a one-off thing, and that they actually have a type. We don't get enough queer awakenings in manga