Sunder for all things also has very low self confidence, he doesn't think he deserves arpi for one thing, doesn't want to fight for her, but he cries that no one can change his kismet. Which implies he will only get her if his kismet is good.
No he doesn't have to provide for her per se, they can be together and equal partners even if Arpita earns and he choose to be househusband, I've teased this topic months ago, it will be very progressive. However, like you say the way this track is being handled is the problem for all viewers.
Neither has he accepted his love to Arpita, nor has Arpita said anything about it, even if we assume they had some bonding which was not shown. In that case it clearly appears imlie shoving him down the throats of Aryan/naramada/viewers.
And reactions accordingly.