I'm not sure I quite followed you there xD But let's see.
No, there aren't 72 different endings at all. I don't even know why you got to that point. A relationship status only serves to, every now and then, change some things regarding a girl's behavior with MC and one or two important details in the story.
Not every character is actually relevant even if it might seem like they are. Not every relationship status necessarily has to influence changes to the point that they need a different storyline.
The line is only one, well, unless there is another bifurcation again, just like the one there already was (and there will be, but that’s a long way off).
Not every earthquake in the ocean causes a Tsunami, and not every change in behavior is so important as to create a specific bifurcation for it.