Turning to anything for the emotional or sexual fulfillment you should get in your relationship is a problem, regardless of if people view it as cheating.
Porn isn't a problem (to some)... Until is causes men to withdraw and consume more and more hardcore content and then only watch it and masturbate and not share intimacy with their wives.
Actually having conversations with AI and sexting will absolutely cause men to withdraw from their partners. AI will be easy, they can train it to say exactly what they want to hear.
We have had a huge problem throughout history of men not wanting women to have opinions, needs and wants... Things like this will just validate those ideas and increase frustrations and friction.
A lot of men are emotionally stunted. They choose not to work on themselves and I absolutely believe they could trick themselves into thinking they are emotionally fulfilled by the AI.
Family time will become a nuisance and their minds will be occupied with rushing back to their phones.
But they will be able to gaslight their partners by saying "it is another form of porn, it isn't cheating" etc.
Honestly, if my husband started using something like this then I wouldn't be able to look at him the same and leave before it began to cause problems (which it would).
If a relationship isn't fulfilling then their energy should be spent investing into their partner or leaving.
I am a huge advocate for healthy self pleasure and sexual exploration withing the established boundaries of relationships... This isn't that. And even if some women may initially agree/not see it as a problem, I guarantee they will think differently after some time.