Some of the threads here adopt the position that Haley's relationship with the MC is causally related to her abuse at the hands of her teacher. While that opinion is certainly made possible by the story line, it is hardly necessary to understanding their relationship, nor does their interaction strongly support it. Of course neither does their relationship deny it. While there remains the possibility that we may get confirmation one way or the other as Haley progresses through her therapy, at this point it's pure speculation.
What is not speculation is that the love shared between Haley and the MC has grown over their shared lifetime. They loved each other long before either became sexually self aware. Twins, whether identical or familial, share a bond like no other. The possibility that such a bond could develop into an intense love both sexual and emotional is quite believable.
The possibility of a mutual ride into the sunset for a happy ending is dependent on either Haley or the MC seducing a beard into the relationship to provide cover, or the willingness of Haley and her brother to end ties with mom and dad. There is little doubt that Haley and her brother are willing to walk away from mom and dad if that is their only alternative. To avoid that we have the dual paths of Haley's seduction of Sandra into a threesome and the MC's seduction of Adrianna into an arrangement that is more practical where she gets what she wants and possibly will allow the MC to be with Haley as well.
The authors will take the story wherever they choose. We are just along for the ride. We, the readers/players, have never had the agency to abort the storyline. Whether white knight or dickhead whatever his flaws, Haley passionately loves the MC without condition all the same. The MC loves her in exactly the same way.
Given a shared unconditional love that has shaped their relationship for their entire lives, what pretexts are available to the authors to break them up? One or both could die. Depending on what the pupster did to Klaus the MC could end up in prison. The therapist could "help" Haley to see that her relationship with her brother is destructive and she ends it. It's worth pointing out that therapy doesn't work like that and there is nothing dangerous nor destructive about the relationship. Either of them could "meet someone" who sweeps them off their feet and cause him/her to abandon the sexual aspects of their relationship. Since neither of them are remotely available for a relationship with a third party, other than as a beard, that seems improbable in the extreme.
The authors, to some extent, have written themselves into a corner. Either they resort to a cheesy plot device, or Haley and her brother find a way to remain together. As I said the ending(s) is/are not up to us. We're just along for the ride and what an enjoyable ride it has so far been.
