The Tell Me Lies series of Hulu revolves around the passionate and annihilating affair of a girl, Lucy Albright, and a man, Stephen DeMarco. Throughout three seasons, they are always lured back to each other despite the fact that their relationship is a growing toxicity. Their college life reveals how dysfunctional things were but it is the 2015 timeline which is almost eight years later, that actually shows the extent to which Stephen continues to exercise control over Lucy. He still plays with her even after all this time, this time by getting engaged to her one-time best friend, Lydia. But nothing, as ever with Stephen, is so easy. The ending validates what Lucy and the viewers had been suspecting throughout.
Based on all that has been displayed in the course of the series, it is evident that Stephen does not do things without having an ulterior motive. To a large extent, his manipulation of Lucy since their meeting has been targeted at her to the extent that she even breaks down mentally in Season 3. Though the scenario of Lucy deteriorates before it is ameliorated, resulting in her being kicked out of Baird and physical separation with Stephen, he has evidently not lost his obsession with Lucy.
After a few years, the band reunites at the engagement party of Bree and Evan, during which Stephen comes with an eye-opening announcement: Stephen is engaged to Lydia. Previous seasons created a conflict between Lucy and Lydia due to the fight with Lydia brother and Lucy lying. Stephen took advantage of that divide and painted himself as someone who can be trusted and Lucy as someone who is not. It is not clear when the relationship between Stephen and Lydia started, but the end gives his motive clear-cut, he was chasing Lydia to avenge Lucy. He was aware that Lucy would be at the wedding and thus wanted to upset her and remind her that he could make her feel something.
Yet, Lydia is not similar to Lucy. Although she early on was attracted to the attractiveness of Stephen, she is comparatively more stable in her emotions and not so impulsive. Lydia fails to offer Stephen emotional chaos and control, which he lives on. The lack of manipulation of her as he manipulated Lucy made the relationship deficient at the very beginning. Nevertheless, when Lydia attempts to rescue the situation, she asks Stephen to get out of the wedding and evade Lucy.
During the course of the event, Stephen is already frustrated. He tries to destroy the relationship between Bree and Evan to no avail despite him leaking out a voicemail that Evan is cheating. He believes that he managed to destabilize Lucy again after having slept with her earlier. However, he loses the feeling of strength when Lucy denies him any interaction. Lydia finally forces him to admit the truth when he flirts with Lucy, and he is finally driven to admit that he only got involved with her to betray Lucy and now that it does not serve the same purpose, he sees no point in continuing to do this.
Lydia is pushed to the limit by that confession. She cannot deny the manipulative nature of Stephen any longer and though she had earlier on unheeded the warnings of Lucy she cannot do so anymore. He might have slept around before, but in any case, the fact that he comes out openly to say that he never really loved her makes the case impossible to ignore. Eventually, Lydia throws the engagement ring at him and leaves him and decides to defend herself instead of being locked in a relationship of deception and manipulation.
