Why is it more difficult for a Mormon woman to control whom she is eternally sealed to? The USA Today newspaper has an article titled "Mormon doctrine leaves potential for 'eternal polygamy'" (reference) that makes the following statement:


  Decades have passed since male members of the mainstream LDS Church
  were allowed to marry more than one wife at a time, but the church
  still allows a man to be “sealed” to another woman in the temple if he
  remarries following the death of a first wife, according to an essay
  at lds.org. However, a woman whose husband has died cannot be sealed
  in the temple to a second man after remarrying.


So based on that paragraph, a Mormon man can be sealed to another woman (if the previous one is deceased) without having to break that sealing but a Mormon woman can not be sealed to another man (even if the previous one is deceased).

An exception to this is if her sealing is broken (a subject in my older question here). But while that is on one hand not a particularly straight-forward, it is also something that is not required from Mormon men.

Because a Mormon man can get eternally sealed to multiple women, there is always the risk for a Mormon woman that in the end she was not the only one sealed to her husband.

My question is:
What is the reasoning (from LDS canon) behind why it is comparatively more difficult for a woman to control whom she is eternally sealed to?
The information I am presenting comes from the newly released General Handbook of the Church of Jesus Christ of Latter-day Saints.
I think the most important section in that handbook for answering your questions comes from Section 38.5 (emphasis is my own)

Members who have concerns about the eternal nature of the sealing ordinance and their associated family and spousal relationships can find peace in the knowledge that Heavenly Father is loving and just. Faithful children who are sealed to parents or born in the covenant retain the blessing of eternal parentage. This is so even if their parents cancel their marriage sealing, have their Church membership withdrawn, or resign their membership.
Members who are divorced but still sealed to the former spouse are often troubled by the thought of that sealing. The sealing will not be compulsory in the postmortal life for either a man or a woman. If temple covenants are broken and no repentance is made, the sealing between the husband and wife is revoked. However, those who keep their covenants will retain the individual blessings provided by the sealing. This is the case even if the spouse has broken the covenants or withdrawn from the marriage.

Given what is said there, I don't think the premise of your question is really correct, that it is more difficult for female members of the Church of Jesus Christ of Latter-day Saints to &quot;control&quot; who they are eternally sealed to. Definitely, as detailed in Section 38.5.1.2 of the handbook, there are differences in practices of sealings after divorce and after a spouses death (as detailed in 38.5.1.3) for men and women. Those sections are for living spouses, see 38.5.1.7 for the cases when both spouses are deceased. The exact reason for those differences is, as far as I know, not explicitly stated in the handbook or Church canon.