...oh I get it. It's almost 4th of July. North America's Independence day. So this shipping is American because Clownpiece's costume is like the American flag. And star sapphire's name is star and the color blue which is also related to the US flag.
I'll be honest since this is a Ooshima Tomo work, I was expecting Nico and Maki (as their parents) to accidentally walk in on their intimate moment and over react on the whole situation.