I was also confused but if you keep reading you'll see that last episode a couple of chapters later
I still don't see anything about their engagement.. maybe I'm blind or dumb
wait let me see, maybe im getting confused as well since I just watched that episode, but I do remember a chapter where the cousin appeared, let me see if the talk about that
ok I just saw and it was chapter 2.6 and they never said anything about marriage,, I mean you can kinda guess there is something but they never said it like in the anime so you're not imagining things
Atleast I'm not going crazy lol
I'm watching the anime and in it the cousin says they were engaged when they were kids but I don't see it in the manga did they just make it up