Since I made the serial publication remark (), one suggestion is that are you willing to trust some editors to know the plot? If not, have you sat down to outline the remaining plot and use that to guide your chapters to help prevent you from bogging on one plot element? If you find you are bogging based on the outline, then it's time to reach out to the editors.
Easy. Don't reinvent the wheel. You're writing and publishing for free. If you're happy with what's already written, people will get over it. There's no need to throw the baby out with the bathwater. People want to see the plot move forward, but a lot of that is based around how bogged down the plot became when trying to build Shane/Trevor's relationship. If it were me I'd probably try to focus on any "relationship building" scenes and see if they can be cut, but I don't think you need to worry about overexposure to other characters at this point.
This is where I think you'd do best to lean on your beta readers and editors in a given situation. Let them know you want to condense your writing, and make the assumption that you have an Intelligent Audience to avoid spoon feeding. Ask them, "Does Kline come across as a prick or are his motivations clear?" Also, do you need him to not be a heartless prick? You want complex characters, but anyone that isn't a central character doesn't really need to be all that complex. (FWIW, I've always felt like Kline was self-serving, but not heartless. I could always forgive his actions specifically because he didn't know all the backstory.)
Have you ever written film or play? I ask because, as the medium is so short, you write with a "once and done" mentality. You tell the audience something in a scene (Trevor thinks Shane is hot, for example) and you don't waste time saying it again. The Intelligent Audience Knows. And when elapsing time or relationship building, you do montages, which you could consider. To be brutally honest, I think this would have cut down a lot of the Shane/Trevor scenes. Sometimes it felt a bit... "Trevor has a nightmare. Shane makes breakfast. Trevor drinks coffee. The boys swim. Trevor is aroused. The boys run on the beach. Trevor is aroused. The boys play a rescue game. Trevor is aroused. Trevor has tremors. Shane is concerned. The boys get a little drunk and go to bed." Then we read it again with slight changes the next day. It would have been faster (but perhaps not better) if you had broken down one day, then wrote a paragraph or three about how they fell into a familiar pattern for the next week, but Trevor still had nightmares and tremors. And about how Trevor was falling for Shane.
The audience would have understood and it would have moved the timeline forward faster (allowing, say, a week to pass), because sometimes from the outside it felt like you were passing time just to make it believable that Trevor and Shane were "in love."
Out of curiosity, is this in preparation for publishing in other formats or just a learning exercise.
ALL that said, one thing to remember is that you have probably hundreds of readers eagerly awaiting your next chapter release. You've had thousands of views. Obviously you've done something very, very right. And I'm pretty sure all of us will stick around until the story ends. That in itself is a feat. I've never written anything longer than a short story, so it's pretty damn impressive. You're doing an amazing job, and I'd be perfectly happy if you stayed the present course.