after experiencing, as usual, a thousand disappointments and delays, from the unaccountable dilatoriness of the workmen, Elinor, as usual, broke through the first positive resolution of not marrying till everything was ready

Apparently, workmen didn't have the best reputation even in JA's time, and in E+E's case too, they caused delays and disappointments. And therefore, even though Elinor had at first decided she would not marry till everything was ready, the delays caused her to think again. As has many other women before her.

So the positive resolution is Elinor's own, but many women have had the exact same resolution - and reevaluation of that resolution - before her due to the dilatoriness of the workmen.