I dont think other than Dev, anyone else will know about this issue... They may show that Dev follows up with other specialist or even better use Google and find treatment options.
He will probably think that he will tell this to Sona after a year or so and then will follow the treatment plan or options.
I dont see any reason for letting Sona know now, as two things might happen
1. She will say No to marriage
2. She is be sad if Dev still wants to marry her
Eventually she wont be able to reply to Dixits with tashan if she knows that she cant bear a child ... that would be depressing...
Dev will not tell anyone and may even decide to let it be for now and will pick up and get Sona treated if needed when they plan for kids
So it will all be happy happy during wedding...I hope they dont show any flashbacks of their junior talks ...
yeah as of now it is just difficulty to conceive .. it is not like she is missing uterus , ovaries all together... so we should also forget about this issue and enjoy the track...
I would also like Dev to really use his selective memory/amnesia and forget about this for a couple of years and have fun... deal with it when they are ready for kids