While everyone was tied up with Blake's drama on — and outside of — Bachelor in Paradise, Demi and Derek low-key became the strongest couple on the beach. Unfortunately, previews for the rest of the season don't make it look like they have a happy ending, but knowing the show, it could be a red herring. And there are actually a couple of clues that Demi and Derek are dating after BiP.
The biggest reason the two may not end up together is that Demi still has feelings for a woman she was dating before coming on the show. Promos for the rest of the season tease that Demi ends up dating a woman on Paradise (presumably the same woman she was dating beforehand) and saying she loves her, which doesn't exactly bode well for her relationship with Derek. The Season 6 trailer also shows John Paul Jones and Derek fighting, and on Paradise, fights usually only happen because two people are interested in the same person. Since JPJ hasn't expressed any interest in Demi, that could mean Derek finds a connection with another woman (maybe Tayshia?), thus starting his conflict with JPJ.
That being said, not all hope is lost for those still shipping Derek and Demi. Here are some clues things just might work out after all.