As for shooting for romantic sequences, let me share a little event from my life.
When I got admitted to mbbs , I was very skinny ,ek to mein hu hi tiny. 😆 So during admission one man told my father , " Isn't your daughter very very thin ?? Can she cope up with the course that is considered one of the hardest professional course ?? "
My father said, If she had the strength to crack the entrance, then she has the strength to do this tough course and she has the strength that it takes to be a doctor.
If Sumbul and Gashmeer are able to do these intense push and pull scenes without any problem, then they can do the " light hearted and romantic scenes " easily, because actually light hearted romantic scenes are much easier to do than the kind of intense scenes they are already doing together.