Hi, I'm a new poster here, and I apologize for interrupting. But I also love this discussion. I started watching DeRo recently, and they have officially become an obsession for me, which is why I've been spoiled all the way to ep. 956. But besides my fangurl love for DeRo and Deniz recently, I hope Roman's part of this particular triangle isn't dictated by the endgame question alone.
I don't have anything that insightful to add, but I think this arc is about Roman feeling incomplete and that his life is full of "unfinished business." And, therefore, neither Marc nor Deniz have any chance of making Roman happy because Roman will forever yearn for something they can't give him. He'll never be good enough, he never has and never will be first place, and this will forever feed into his insecurities, deception, self-deception, self-sabotage, etc. The lying is an extension of this as Roman lies in order to take what Roman himself would call "the path of least resistance." What other choice does he have but to lie? If he tells the truth, then he'll have to explore WHY he's afraid of leaving Deniz and WHY he can't let Marc go, issues that may or may not be tangential to how he sees and values himself. So lying is comparatively easier, or at least that's how I fanwank it.
All of this makes Roman a tragic character. Or at least I find him tragic because he doesn't realize destructive his self-loathing is to himself and those closest to him. So at the end of this triangle story arc, I want Roman to be alone. While it will break my heart, I want DeRo in shambles so that Deniz and Roman build themselves back up as different people. I want to see Roman forced to change the way he views himself and to one day be more appreciative of the people who have supported him, and I don't think that will happen unless he loses much of what is important to him, whatever that may include. Because in the end, despite his traumatic childhood and the traumas and disappointments in his life, Roman can have a great life even if it doesn't look like he thought it would. He just doesn't realize that.