“This “remedy” doesn’t make any sense. I’ll repeat, what happens to Bechirah Chofshis? Either a Chassan or Kallah’s Bechirah Chofshis for their entire lives is removed if one of them does this at the wedding? Come on. It defies logic and basic principles of belief.”
What these medrashim, etc mean is not that you lose your bechirah, but rather that it is much harder for you to choose one of the options – ie harder nisayon. For example, someone born from a woman who doesn’t go to the mikvah [meaning born from niddus] will have bad middos. THis means that rov will bec it is a much harder nisayon. And further, ahen a gadol gives someone a bracha that he become a tzaddik, that doesn’t mean he has no free will, just that it will be easier for him to achieve it. Ramchal in Derech HASHEM spells this out – (loose paraphrasing) – “Gazrah B’chachmaso HaElyonah that some people will get siyata dishmaya and therefore be able to achieve shlaimus more easily, and some will aderabah will min hashamayim be put into very trying conditions that will make it much harder to do so.”