I've finished three novels. You might try story analysis.
Instead of just reading your book, try to relate it to three act structure. You can find some fairly detailed versions of this that also break the acts down into several beats. Personally I consider four equal acts; I, IIa, IIb, III.
I would stress that this three act structure is not some dictate from Shakespeare or something, it is actually a pattern distilled from hundreds of successful stories, by analysis. This is, roughly, what makes stories 'work', it is some kind of reflection of the human experience.
Your trepidation to finish may come from your subconscious, perhaps you have not met an implicit promise you made to the reader. Try to figure out what went wrong with your story.
Stories open with describing the hero's normal world.
In the middle of Act I some incident, by chance or mistake, leads them to a problem.
Initial attempts to solve the problem fail, the problem intensifies, and by the end of Act I, the hero must leave their normal world.
Your story doesn't have to follow this formula precisely, but roughly the kicks in face demanded by the three act structure are necessary to build sympathy toward your character, so in contrast their happiness means something later.
Whether you are a discovery writer (like me), or follow a written plot, chances are your story follows the basic three act structure, it is the natural form of successful stories.
As you write a story, you make some implied promises to your reader. These can also be subverted, but eventually some of those promises have to pay off. The villain (even if not a person but nature or society) is defeated, the original problem that drove our hero out of her normal world is solved, she either returns to her normal world and resumes her life, or she forges a new normal that promises (for the reader) to be satisfactory. She has romance, or she is reunited with her sister, or whatever. The bad guys are busy turning into dust, or at least have moved on.
Don't just read your story. Analyse it, scene by scene. What is this scene FOR? What change does it accomplish, in her thinking, in her knowledge, in unraveling some piece of the problem.
Sherlock gets three scenes leading him to his primary suspect, and one confrontation that convinces him he's got the wrong lad. He's shocked. Back to square one. Kicked in the face, metaphorically speaking. A scene of frustration, to show Sherlock is suffering. But then, recovery -- A realization -- If that lad didn't do it, then ...
Each scene should advance something. A plot, or subplot. It can be an important character trait of one of your characters: Often this is a promise that this trait is important. We show off Sherlock's superhuman memory and attention to details very early, as part of the Normal World, even in some relatively inconsequential setting. We do that because the plausibility of the entire story relies upon those superhuman abilities, we can't spring these abilities on readers as a surprise halfway through the book. It's why every sSperman movie begins with Superman and quickly switches to Clark Kent in the first few minutes (or vice versa), we don't follow Clark Kent halfway through the story and then find out he's Superman.
If I have writer's block I presume it is my subconscious telling me that something does not fit, something is wrong or inconsistent. Maybe it has become boring, I have been too easy on my hero. Maybe it isn't turning out right, and I need to rewrite something. I turn to story analysis, even writing a scene breakdown of what has happened so far, why I felt the scene was important and what it accomplished, perhaps in analysis later I can connect that to the story.
It doesn't have to be complicated. What happened in the scene? Why is that needed, or what does the reader know now they did not know before? What are the ramifications of the scene? As a reader, does this scene make you expect something later (i.e. is there an implicit promise in the scene?)
Good luck.
