Separating Simmons and Fitz in such a seemingly insurmountable way certainly gave Elizabeth Henstridge and Iain De Caestecker the chance to flex their acting muscles, and it was definitely one of the most creative plots that the Agents of S.H.I.E.L.D. team ever dreamt up for the series.
I’ll admit that I thought the effect of the rock turning to liquid at odd looked pretty awesome after it was introduced, so kudos to Jed Whedon and Jeffrey Bell for coming up with a big mystery at the end of Season 2 and through the first half of Season 3.
Besides, if the show was going to go all-in on the Fitzsimmons romance, there was really no better way to set them up than Simmons spending months talking to an absent Fitz because she missed him and Fitz literally finding a way to jump through a rock to retrieve her from another planet.