Tumbling, my H behaved the same way when we spent time together during our separation. Like nothing wrong was happening. No R talk, just enjoy our time together. Just four weeks ago we had an amazing day together. I thought this was good news, but he recently said he still wanted to see what it's like being with other women and might file for D.
We have only spoken once in the past 22 days--and that was to express the "need to date" thing.
It's baffling. His behavior makes no sense.
What I would say is that WAS's behave in very similar ways, and finding a reason won't help. DB techniques will help those who have just started on this journey, but I don't know how effective it is for long-term situations--like ours. Who knows. Don't mean to sound too negative, but that's my honest assessment at this point.
At least know you're not the only one who's going through this.