Your story doesn't sound plausible to me

By the time you'd entered your first creative writing class with the specific intention of writing stories, you'd already had familiarity with a key concept, "willing suspension of belief," and a French word for yet another concept, the unknotting of denouement.  

Over the years, "willing suspension of disbelief," while of vital importance to you, has been replaced with a synonymous trope, "the point where the reader stops asking why, and begins asking instead, 'what now?'"

You like denouement well enough to have learned, way back then, when your spelling was, on a relative scale, a six or seven to your contemporary one.  This does not mean you forswear the spellchecker or the dictionary.  This means your memory, which has always been good about such things, has been put to some practical use beyond memorizing historical dates for historical events.  This also means you substitute the French word for unknotting with a term you more associate with music, resolution.

A favored approach you put to use when in a teaching mode is to ask why as you read or listen to a story being read aloud.  From years of doing so, you've honed your own sense of story as well.  The reader should by all means remain curious, but the curiosity should relate to why the personages in a story do what they do and don't use other options.

At about the time of your introduction to willing suspension of disbelief, you were still a good deal more stubborn than you are now.  If you were the one being questioned about some behavior or attribution, your answer often fell within the narrow parameters of "Because I felt like it," or "Because [the character} felt like it."  Idiosyncratic certainty is not enough, was not enough even then, and the more you used that response as an answer, you knew it was not enough to satisfy the larger overview of dramatic integrity.  "I felt like it" was a cover-up for you not having done your homework of understanding the complexity of the character, and of relying on the rhetorical force of your, "Because I say so" as offered proof.

By the time you began editing and teaching, you'd begun to collect the experience of writers, many of whose work you admired, having sufficient reasons for the why questions.  In due course, you saw the correlation between the writer who knew all the details, the writer who did not feel the need to use them all simply because she'd gone to the trouble of acquiring them, and convincing sense of presence in story.  You then became fond of the word plausibility, which you continue to use in this context.

Neither you nor any writer you admire have much success arguing potential readers into suspending disbelief; the condition is not based in rationality.  The condition is based in concern for the characters, their goals, their motives, their focus on the matter or matters at hand.

For some time, although you thought you understood and appreciated the need to lure the reader of your work into suspending potential disbelief, the circumstances were of a piece with younger times, where you were introduced to tools whose function you understood, but, for instance, why would you ever choose to employ an Allen wrench, and what reasons could you have for using a lathe or, for that matter, an ohmmeter?

Getting the reader to stop asking why is a major matter in the craft of storytelling.  How is she going to do what she intends? is a batter way to look at the problem of plausibility.  Empathy rather than artifice is the better technical approach to the problem.  Action rather than description brings the matter to a visual intensity.

Accomplished storytellers and crafty opinion manipulators understand the need for the emotional response, which sometimes requires few words and a picture or symbol instead.

The reader shouldn't have time to think things over, a moment or two of time to decide whether to believe or not.  The reader should be too concerned with what will happen next to have the time to test the circumstances for logic.

Motto for a tee-shirt logo:  I thought I was getting a story I could believe but all I got was this lousy excuse.