Unfortunately anytime anyone pretends to be something or to be ok with something that they are not-it matters not WHY they did the pretending-there will be fallout.
I think a lot of people forget, even in poly where we SAY it's all about honesty, that honesty doesn't JUST mean being honest with OTHERS, it also means being honest with OURSELVES.
If you think "could I.... would I.... ???" and the answer is "IDK" then you have no business moving forward until you dig a big deeper into yourself.
*****not ragging on you OP! This just seems to be what happened with S and thus I thought maybe some other reader would find this helpful to avoid the mistake and pitfalls S made causing this heartbreak train for all of you******
Only when you can know YOURSELF fully and honestly are you ready to start sharing yourself fully and honestly with other people.
Yes I know we all change-that means this is an ONGOING responsibility to "keep knowing yourself"!!