Unless I am mistaken, this drama relies on a pretext that is lintrinsically flawed: The main tenet of this drama is that Stephen Briggstocke seeks revenge for the death of his son after Catherine Ravenscroft seemingly "used" him. Given there sexual liaison was behind closed doors there is no obvious way in which Jonathan's parents could have known the details of this or the nature of his death. This undermines the whole story and yet most reviews appear to have either missed this or overlooked it.
In addition, there are scenes that simply do not hold true: her colleagues at her work turn against her, in an instant, because a chap appears and makes allegations against her. Her Husband of 25 years sides with this same old chap against his wife without any explanation as to why he is so disloyal and we are led to believe that this same old chap can pose, quite successfully, on Instagram as a teenager, without raising any suspicion and managing to build a relationship with someone he's never met within a few hours?????
It's a shame because this drama began well and had the makings of being a good story, with great actors but ultimately the premise is flawed and the characters simply don't act as people would.