Although I wouldn't be surprised if Ioan did cheat, by the same token, I actually wouldn't be surprised if he hadn't cheated on Alice. The way he's behaved throughout the divorce, he seems to be a genuinely decent man and he's bent over backwards to make things easier for Alice until she abused him and Bianca past the point of tolerating any more. She emasculated him so much that I can see him falling into bed with any pretty fan who made him feel good about himself, but he also seemed to genuinely love who he thought Alice was and to see her with rose coloured glasses for many years. Ultimately the only one who knows whether he was faithful or not is Ioan.