I got stuck trying to figure out what it means for two people to sit evenly spaced between each other... Off to google before I can continue this chapter!
EDIT: Goddamnit, it was a line spoken by tadano, not the guides thoughts regarding the distance between tadano and komi. Seems they refer to the space *between couples* (and more than two couples) being the same. A natural conclusion from people sitting along a length of space but wanting to keep their personal space, so when they arrive they always pick a spot that is furthest away from the closest strangers (maximizing the min-distance).