I have seen most of the comments like PROPOSAL WAS NOT GOOD. My POV is below. Please forgive me if I am wrong.
I think it was O.K friends. Instead of dragging things, simply crying, asking for forgiveness, since both of them had truly understood themselves and they were inseparable. Dev had shed all his feelings on the engagement day and equally Sona also had shed her feelings.
There is no need to ask for forgiveness which the give themselves when not asked for.
I think Kuch Rang is not dragging the story like wedding for 2 weeks, 1 episode for 1 proposal, 1 for break up.
And I need to mention that Dev had told - that he his a difficult and complicated guy. So this was O.K.
SO, I THINK THAT HIS PROPOSAL WAS O.K.