if you follow BW you can see any post she liked of Alice, it starts in november 2018 (that's when she probably became an extra on Harrow) and stops in may 2019 (during that time Alice was visiting Ioan in London btw)
Ioan was in 2019 in Oz until early march, but she continued liking Alice's pics till may. to make this theory work she and Ioan would need to already be in contact
If we want to construct a theory out of the liking angle I think till may 2019 she was just proud to be on the same show as a international star and a bit of a fan of his, thus also following his wife, all very innocent. Then her marriage started breaking down and she felt bad for liking pictures of the wife of somebody she has a crush on, now that she is about to become single. I definitely dont think that the affair was there yet (neither does Alice fwiw)
With the evidence/theories you've provided over the last couple of months Welp and also with what Bianca has recently posted, I can't see them only getting together after he told Alice he wanted a divorce.
Ioan has made a pretty big commitment to a woman that has very serious health problems and who is going to need some really serious care as her health continues to decline. I really don't believe that is something that you undertake lightly. You have to really 'know' the person behind the illness to love that person and see beyond the illness to make that kind of commitment. She has moved to another country to be with him, she had left family and friends behind and will be on her own for long periods of time when he has to take up offers of work. That isn't some overnight love story, this has taken some serious, long hard 'get to know you' kind of work.
I won't differentiate between an emotional affair and a physical affair here because both are equally destructive to the person who has been deceived. So whether they started physically shagging before or after Ioan told Alice is not the issue. It's about the time it must have taken to build that really strong connection and commitment because they both know longer term what that is going to entail.
In some respects it could be viewed in more black and white terms if you knew your husband was just having a bit of light relief pumping away at a wanna be actress a few times a week. Viewing it as a physical, getting rid of some pent up hormones kind of thing . But knowing that he had taken the time to slowly fall in love with and make a longer term commitment to a seriously ill woman behind your back would feel like the wind had been knocked out of your sails.
I feel a bit towards Bianca like I do towards Alice now. I felt sorry for Alice in that Cameo video but also hold firm in my belief that she really has acted in some
crappy ways. With Bianca, I feel pity for her having MS, other ailments and her bleak future but I also think that if they did take the time to build this relationship behind Alice's back then that's a really
crappy thing to do. You don't go grabbing 'your best life' at the expense of anothers. If this is how this 'postive' stuff works then it seems to be more about focus on self and what's in it for me rather than being a decent human being being decent to other human beings.