I haven't read any of the other comments. I suspect that this chapter, as did the preceding ones, generated many well reasoned even passionate responses. That's to be expected as you've done a remarkable job crafting a very different type of story. I previously teased you about being a hopeless romantic who uses love to redeem apparent lost causes. I'm not certain even you could fix this relationship or that you should. There are such things as lost causes and I believe this is one. The relationship Chase and Hank shared is over. Neither is the man they were when the story began. Chase has grown out of a depressed dependent state to become more self-aware and self-reliant. He has accepted and assumed responsibility for his actions. While he still cares deeply perhaps even loves Hank he seems capable of moving on. Hank seems diminished. He refuses to believe anything but what he "saw". However, we know from Chase that what Hank thinks happened is very different from what did. Hank knows that Chase is in therapy. That Chase is working to resolve the issues around how his mother's illness and death effected him. How could he so quickly dismiss survivor's guilt as nothing but a conjured up excuse? I think his certainty is his way of absolving himself of any responsibility in the demise of their relationship. Any doubt of the correctness of his viewpoint makes him equally culpable. He also seems to have a very limited ability to trust. Rather than be willing to accept Chase's explanation and apology he seems to want to believe the worst. The inexcusable and just what is the inexcusable, that Chase might have cheated or that Chase had the termerity to reject his proposal?
We know very little about Kevin other than he was devastated after his partner cheated on and left him. Has Hank found in Kevin someone he can be "strong" for, to provide support to and nuture. Is Hank the sort who only finds his strength in another's need? Seems quite possible.
The limiting factors for our better understanding is a lack of forestory on their early relationship and Hank's viewpoint.
Still, I don't much like Hank.