Dating culture is actually pretty different worldwide. While I don't think it's usually very wise to date your coworker, here in the Netherlands it's actually a fairly common thing. That being said, I have no idea what it's like in Japan. But I've seen a few anime and read a few manga where the parents did meet while working at the same company. And there's also a decent amount where the parents run a shop or business together, so I don't think it's completely taboo.
As for whether HxH is gonna kill off a major main character... well, have fun finding that out yourself while watching it. Well okay, maybe it wouldn't be that fun. Either way, next episode will be a good watch (okay, every episode so far has been a good watch).