Hmm honestly that could be a possibility at this point as we know absolutely nothing 😆
So here's my theory which I mean is what I would want in the ideal world of this show but it probably won't happen 😆
I think Pooja was faithful, but Yash was the one who wasn't. Now hear me out. With the emphasis the show is placing on the mystery behind Pooja: her diary, her frequent trips to the hospital, how and why she knew Yash, I think it may go the opposite route. She may have been ill and she may have been hiding some secrets from Aditya, but they could easily have been things to protect him. She may have met Yash through business dealings, knew him from the money invested in his company and all that. They may even have been friends.
However Yash has been depicted, even with Zoya's biased memories, as the perfect husband who has loved her and didn't stand to gain anything from marrying her. But we know he'd bought a ring that wasn't for her, we know he kept secrets from her and we know that he's kept Zoya away from his life in Mumbai, so why?
Pooja's secrets have been incredibly obvious, Yash's haven't. Yash may have had an affair but it isn't necessary for it to be with Pooja.
The only reason I like this theory is how it could go with AdiYa. With this theory both Aditya and Zoya are wrong. Zoya's blind faith in Yash is wrong and Aditya's blind hatred of Pooja is wrong. The ramifications of this would be so interesting to see. Aditya coming to terms with his behaviour and own darkness only to realize it was for nothing. His repenting and coming to terms with his wife very much being faithful is going to shift the world he's built for himself at this moment. It's going to kill him inside to have doubted her.
Likewise with Zoya the blind faith, the rose coloured glasses through which she views the world is going to be the same. Her faith shattering is going to be just as big of a blow as Aditya's being restored. Seeing her break down for different reasons than Aditya's owns will bring about an ironic juxtaposition in both their lives.
Zoya's grief and turmoil vs Aditya's grief and self-loathing. Zoya's entire world falling apart vs Aditya's world coming together. Who will help whom? How will they come together after this? How can they heal, together?
Just my two cents and musings 😆