At that point in the storyline, he wanted to completely ignore the marriage, go on with his life like it has never happened, he called it a nightmare many times.
He should have annulled the marriage first thing after coming to Delhi, it'd also have given Imlie a sense of closure and ultimately benefitted them both. Plus it was the morally and ethically correct thing to do before marrying Malini. His ostrich approach is that one of convenience and cowardice.
But Aditya is not a hero material. He's a common man, like any man in India. We can't expect him to behave perfectly or even appropriately in most of the times , we'll only set ourselves up for disappointment. Except good looks, a swanky job and good education, he's no other qualities that make him special or a hero. There's a certain charm or fascination about his character, not inspite of that, but because of it. He can react to a certain situation in any whichever way or the way just a normal day to day common folk would do.
This is the era of unheroic heroes in ITV . If done well, he can set a trademark in here to bring in more realistic and next door neighbor type heroes instead of the larger than life Shivaay Singh Oberoi, Abhay Raichand, RK , Dr. Armaan or Dutta Bhao type. It's a shift from Amitabh Bachhan to Amal Palekar. Both types have their merits.