If i remember right Jack can be a "good end" for Ashley and is actually a decent guy at heart. Perhaps this is a path where Ashley ultimately betrayed him and chose his brother (or they never got together, if Good Jess is in the game) so maybe he can be a decent outcome for Lena in this one.
As for Robert, he continues to show he's a dick who blows up at the smallest opportunity even in this epilogue. His role is to be a loser, and he's embraced it wholeheartedly.
I agree Robert is a loser, he is supposed to be in this narrative, and there is nothing wrong with that from a story telling persepctive. I'm just saying with a little tweak in the begging of the game there is a world in which Robert could have filled that roll of boyfriend to Lena so she can have a healthy male relationship with someone other than Ian.
While we're on the subject of Robert being a loser though. Something that I've have always felt was a missed opportunity is Lena's and Ian's reactions to the Robert fight at the museum. Ian always regrets the fight, even if he initiates it with a shove or taunt, when it could have been used as to solidify his increasingly "alpha chad" mindset. It's kind of what the Milo fight ended up being, but to a much less effective extent. Or Ian could have spent more effort trying to talk Robert out of the fight, but Robert's pride or ego basically forces the fight and Ian could have delt with him again in a similar, but more effective way to Milo. Ian spending an extra dialogue option trying to talk Robert out of the fight goes a long way to show that he's a more mature and responsible person, worthy of a good Lena or Holly.
Then on Lena's side of the chapter. Lena mocking Robert for not being "man enough" to win a fight against a "writer" would have made for a more satisfying break up in the moment, as well as emphasizing how manipulative and bitchy hooking him up with Holly is later. Holly then later dumping Robert for similar reasons in a future chapter or epilogue can also re-enforce just how much of a loser Robert is and how far the claws of Lena and Ivy have dug into Holly. Lena telling Ian how exciting she found it afterwords could also work towards explaining why Ian and Axel start to square up in chapter 10 rather than attempting to talk it out. Or if the player lets Ian lose, Lena mocking him about not being man enough could sow the seeds for the cuck path later. A more decent Lena could berate Robert or Ian for starting the fight, giving her an exit from either relationship, or can help deepen her relationship with Ian if Ian spent that extra dialogue option trying to talk his way out of the fight earlier in the chapter.
I don't know it was just such a dramatic high point in the story, and very little seemed to come from it.