Bubbie Tex – I am so sorry about your difficulties and pain. I am sorry you had such an awful experience.
As far as answering the question: “Why is it so?” I don’t think I can agree with many points in your premise that that is actually how it is. Especially saying, “suddenly no other man wants to “take on” her children, who are no longer considered blessings”. That isn’t fair. It is not as if you line up your children and a future chossen says, “eww”.
Not everyone is capable of raising teenagers they just met, not everyone can afford an additional 6 kids to their own 5, not everyone can jump right in to the parenting system that the mother insists on even if it isn’t working or is different than their own. Not everyone can handle taking on 4 new children when they can hug two of them but have to leave the house if the others are home alone (yichud issues). And what if one girl is rebellious and insists on dressing provacatively? It is not so simple. There are so many things involved in marrying someone with children, and to present it as if it is just a “non-preferred” status is not fair to all those men who are willing but unable.
I do believe your experiences are real, and will not argue that at all. I am just offering that (as I have seen from personal experiences with friends)the inferences may be incorrect.
B”H you found a prince after all!