I liked this one too, it was about on par with the second episode for me. I liked how I spent most of the episode thinking Liam was a dick that was accusing his wife based on the flimsiest of evidence, but then you realise that this was based on suspicions that have been bubbling in his mind for over a year that were justified. It, ironically, brought back memories from my own past that I'd rather not remember.
I've seen people complaining elsewhere that they didn't fully explore the concept and how it would be used by the police or whatever, but I liked how it used the sci-fi concept to tell a smaller character story. Seeing how technology affects society as a whole can be a treasure-trove of good storytelling, but exploring how it impacts individuals and their relationships is no less important.
Also, that sex scene where they relived a past, more exciting sexual experience was one of the most disturbing sex scenes I've seen in a while, which is saying something considering I watched a Prime Minister fucking a pig two weeks ago.