A bunch of things on their FB pages have been removed since this whole thing started.
Lauren's page hasn't changed. Same exact photos from when she uploaded them. The BF has now restricted access to his page (understandably). Prior to this restriction, he only had 1 photo of them together on there (which is now his profile picture but wasn't until after her death).
I don't think we can know their degree of seriousness for sure. They just don't appear to have been that serious based on the only evidence of their interaction that we can see.
I know it makes it more dramatic to ascribe a huge relationship but honestly I think that is a distraction to this (especially with every couple of days on here someone new points their finger to the innocent, out of state boyfriend).