The problem of course being that then Arthur would then mention his crush on some girl in class, or Merlin would get a call from his fringe benefit/girlfriend/sugar mama/shut-up-we’re-complicated-like-a-freaking-Celtic-knot-type-person of the month (Merlin was a heartbreaker. You wouldn’t think so, but it’s always the innocent looking big eared ones) and the observer would realize that Arthur and Merlin—while being the more adoringly boring couple ever invented since ever—weren’t actually dating.
Yeah. That’s right. Even when they AREN’T ACTUALLY DATING they’re still the most adorable couple ever.