I agree with @FaFoutis. I think that many women go into step parenting thinking that they can be good step parents, but on the whole women appear to lack that ability to take on children from someone else and have and maintain decent relationships with them.
FWIW I think there are also men out there who don't make good step parents either, however IME and IMO the difference between men and women is that most women would not tolerate a man who expected her to put him above her kids so most men with that attitude are likely shown the door very quickly. However men are more easily influenced into believing that the woman and/or her own children who live there almost full-time should take priority above the children who are only there as part of a contact schedule, and are less likely to fight the breakdown of a relationship between them and their children.
As for the OP, this is a woman who: married a man only just over a year into their relationship (she said they have been together for two years and married for ten months, that's hardly any time at all,) has said quite publicly that she believes children should spend at least one weekend a month with grandparents to give parents time off, and should go to boarding school.
Clearly she wouldn't even make a very maternal mother so it's not exactly a leap to think that the step mother role wouldn't be for her.
And the answer to that is, if you don't want to be involved with a man's children then you don't marry a man who has them. And yes of course the father is at fault here, for allowing his wife (how many wives has he had now?) to dictate his arrangements with his children.
Yes, it's hard if the mothers move away, but come on, the man has two women who are prepared to block access, really? We are to believe that not one, but two women are such psycho's that they're prepared to cut contact between this man and his children for no apparent reason?
I am usually the first to say that of course there are women who do block access, but if all the women are blocking access or threatening to unless it happens on their terms one needs to start asking the question as to why that is. Because if it really is them then the man has poor judgement and needs to stop jumping into marriage on a wim, and if it's not the women's doing then the man isn't telling the whole truth here and women need to stop marrying him on a wim.