I am not sure if the ex was directly involved, as it does appear they all 3 knew each other quite well and had no problems together at some point. But these types of relationship can often be complex, and can go sour, sometimes horribly so. I know I have hypothesized the ex was involved, which could be as innocuous as knowing a piece of information the rest of us don't, or as sinister as planning something, it's hard to speculate.The online activity of the ex raises eyebrows, though not necessarily is proof of anything and could just be truly unfortunate timing, but shouldn't be overlooked given the circumstances. Some of the information in question was removed in the last few days.
KB and NN became friends on a website the morning the couple went missing. KB uploaded a photo the evening before. NN commented on the photo on the very evening the couple went missing, complimenting it. A month or so before, NN had commented on a particular dark piece of creative writing, and then commented again around the time of the disappearance, those comments were removed yesterday. That piece of fiction was written by a man who NN listed herself as having certain types of relationships with a few weeks after the disappearance, all of those comments and references were removed yesterday. That man also posted a comment yesterday that someone is starting rumors about him.
And as mentioned elsewhere KB had asked about becoming a cam girl or getting paid to play, the day before they went missing. Is any of this relevant to them going missing? Who knows, but it's a bit suspicious, yes? Who is innocent and deserves privacy and who knows something? Hard to say...
Could all of this relationship stuff and what not be irrelevant and they just ran off the road somewhere going to grab dinner? Maybe. However, his account being active with the posts, and then a few changes on other social media profiles after they went missing would indicate to me they either disappeared willingly, or unwillingly and someone got access to a laptop that was signed in to multiple accounts. If they just ran off the road somewhere without involvement from others, I wouldn't think these particular updates would be made.
Anytime in cases like this, you end up chasing information down strange paths until you find the right one.