Weeellll.... They did this: cdn2-www.afterellen.com/assets… and then the series ended, and the writers confirmed them as a couple. Betrothal necklaces and post-engineering-cuddles just follow naturally from that.Also, watch it watch it watch it! It's an excellent show with some fun worldbuilding, excellent animation and fighting, and mostly three-dimensional and/or likable characters (be warned though, season 1 and 2 are the weakest of the bunch). And, as I just spoiled, it has the best resolution to a love triangle ever