Dev is not a teenager who is ruled by his hormones. He is an adult of 28 years who promised a woman that he loves her like a man loves a woman. Now he has his reasons for not keeping that promise and also breaking up with her. We can analyse his circumstances, upbringing or what not to understand the why. But the fact remains that he is an adult. He should not allow others to dictate decisions in life. He has to take responsibility.
The mother - son relationship had always been selfish and this has affected his siblings quite drastically especially Neha. Doesn't his sisters deserve better. Dev is also responsible if not in full in part.By understanding and pointing out his follies doesn't necessarily mean hating or bashing him. I for one love the character of Dev . But I am not blind to his faults. He is not a devil but nor is he an angel.