this is probably one of the many reasons for failed marriages. What we need to focus on is effort. Sona is making an effort and i would like to believe that even Dev is making an effort. Both may be failing but the intent of making the effort should never be let go.
Dev needs to talk or make the effort to talk - to Ishwari. She has to be told that he is no more single and that he is now a husband too and a husband has certain responsibilities to fulfill. Ishwari knows about it but needs a reminder. I liked how Sona spoke to Ishwari today. it was not a confrontation but a sort of level headedness that was factual and devoid of any accusations or blame.
Yes, Dev has to learn and learn quickly.. he should make every effort to resolve his own inner conflict. Example - the spoiler. If Ishwari made arrangements for his birthday, the least he could do was tell his mom that he has to pick up his wife who is waiting for him. Nothing wrong in that. Instead he sends the driver!!!! Now this is not effort being made.