Rhea and Rishi were happy ,outgoing and fun people who had a very different attitude towards life as compared to Dev and Maya. You can also see that in the end Rhea was happy being a mother and maybe drifting towards another relationship but it was motherhood that she chose at that point and was happy about it. Rishi moved on , fell in love and was getting to be happily married.
Both Dev and Maya were extremely flawed and had deep insecurities. They never made the effort to communicate to their respective partners because they thought they could not understand them without even trying. They never tried to be happy and with each other found a kindred spirit of revelling in that victimhood.
Dev on his leg and career and Maya never really loved Rishi more as a childhood friend and she went ahead with the marriage to keep Rishi's father happy. Also her not able to become a mother ,her perspective on that was never fully shown was she okay to not be one or was that a problem with her.
The marriage would have lasted but unless both underwent therapy they would not have been very happy because both of them had very strong insecurities and issues.
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