It's been a constant theme in Fuzoroi that the girls are mismatched in almost everything, but their relationship still works somehow. It's literally the title.
I don't know why people act surprised when the author reminds readers of it.
Heke is an irresponsible and scatterbrained mangaka with the brain on sex and games, while Shinohara is a career woman focused on "perfection" (as a gamer, at her work and in her daily life). But as the saying goes, opposite attracts.
In their relationship, Heke makes efforts to work harder and Shinohara makes compromises, like allowing her to live with her and giving her rewards. Because they love each other.
So, they somehow complement each other and are learning along the way.
Not every couple has to be lovey dovey and fusional. I think Mikanuji's couples ring true.