I had a situation similar to this. The parents had recently separated when the child started with me. After a year, his play changed (mom and dad lived in the same house) and I noticed his parents were seeing each other a lot more and appeared to be getting along for the kids (which it wasn't clear whether they were just moving on or the fresh wounds had healed). I mentioned to them that his play had changed and he may be confused about their relationship. They just smiled and told me a couple of weeks later that they were back together and buying a house together. It could have been more awkward, especially because I had no clue they were together, I just figured they were getting along. This was such a brutal divorce too. They sold their house, divorced, fought all the time then got back together and bought another house.