Shalom,   According to Zohar mishpatim and arizals teachings there are multiple factors which can complicate the matter. 1-we must know how the two husbands completed their rectification  2- We must consider the idea that she might have more soul work to accomplish and need husband number 3. 3-Perhaps husband 2 completely finished his work and is her true soul mate and they are rejoined  4-Remember that’s soulsparks are combining so no one person is just one spark and rather an amalgam of different sparks.   I hope this helps  R.Yosef Karpman