tbh i think with something like the end of your marriage, you can always find a reason to try and not say it is done, as you are so aware of the implications and how painful it will be, and being a person who cares about others feelings, you try not to hurt them.
even if you know that by staying you are ultimately causing more long term pain
as much as i was sure my marriage was over and done with, it was still incredibly painful to stand up and actually say that to my h, because i just didnt want to cause so much pain to him and the children
but it would have been more damaging to them in the long term if we had plodded along in a marriage that i felt was slowly killing me
now that may sound selfish but it isnt, as i couldnt bear the thought of not only my future being irreparably damaged by staying with him, but by the kids seeing a destructive relationship and thinking they might repeat that example in their future ones
and my exh had to realise that his behaviour was not right, which would give him a chance to rectify that with any future relationships he might have
i just didnt want them crying one more time when they thought we were rowing, it was breaking my heart and theirs