I think Ioan is an old-fashioned, involved, loving dad who set boundaries because no one else in that house would. He did the heavy lifting with Elsie's homework, played with the kids, took them to school, and made their lunches while their mother loafed around in bed all day. But I'm not sure that he understands emotional nuances. If he did he wouldn't have stayed with Alice for as long as he did. There was definitely some kind of Stockholm Syndrome going on there, his involvement with the cult church shows that he is a prime candidate for that. He has been a paid-up member of The Alice Cult for 20 years. I don't think he was aware that he was a victim of domestic violence until the last years of his marriage when he was in Australia and around normal people and then told by his legal team and his therapist that he was.
Ioan is still that old-fashioned dad who is having a not very old-fashioned divorce played out on social media. He is recovering from decades of abuse and still trying to set boundaries and be the same Dad he always was to his girls because his love for them hasn't changed, but I am not sure that he has the emotional insight to recognize that any new partner is a difficult situation for children to navigate in divorce and that his children do think his love for them has changed and will be pushing all the boundaries for proof that it hasn't.
Ioan is a serial monogamist who when he is in, is all in and he is all in for Bianca, who is a loving, kind partner who adores him but I don't think he understands how any child would find it difficult to adjust to a new partner, let alone kids that are subjected to indoctrination. I know he had to factor in Bianca's medical condition but them living together weeks after the relationship was announced would be difficult for any kid and his kids won't know the reasoning for the swiftness. He doesn't fully realises moving in immediately with Bianca after months away is one of the factors that has damaged his relationship with his girls.
They literally do not want any mention of Bianca, they have their mother constantly ramming her down their throats and they don't have the emotional maturity to not think that their dad is prioritizing his girlfriend over them. He is getting on with living his life as he should, he and Bianca have been living together for a year and this is how things are now. Unfortunately, his mad ex has denied his children the right to gradually get used to the new normal. Bianca is still an unknown who according to Alice has lured their father away and wants to kill them, who gets to go on the fancy trips they used to go on, and who according to their mother is preventing them from being with their dad.