Imagine these three together.
Kolivan and Adam are no-nonsense people. Kolivan is more strict than Adam but they're still very similar personality wise. Shiro isn't a no-nonsense person, he's still strict than needed but he's able to easily adapt while Adam and Kolivan are either unable too or would rather not.
They'd also just be very sweet together.
Shiro already knows how to interact with Adam and Kolivan in a more intimate way due to the fact that he spent a good amount of time with them. Adam and Kolivan would be more clumsy with each other, they don't know each other well enough for their more intimate actions to come off as naturally as Shiros.
The three also have movie nights where they cook things like muffins or cookies for snacks for their date nights. Adam does most of the baking(with help due to missing a few limbs) while Kolivan and Shiro set everything up.