That's my main problem with the cuck route: the whole playthrough is super depressing.
There was an interesting idea to explore - and I still suspect it was EK's initial intent - which was for Ian to exorcise his trauma from being cheated upon, via the sublimation of the woman he loves fucking someone else with his consent; while Lena would exorcise her pain to be cheated on and fooled by being in control and being the one who cheats, but with her boyfriend's consent and before his eyes.
It could have been as well narrated and written as the vanilla route and the trouple, which are the best-written and designed paths for now.
Unfortunately, a far too slow slowburn, updates every jubilee, and the off-character vulgarity of the cheating Lena have spoiled it all.