I can picture this after the twins were born since she looks very tired-baring 7 sons can take a heavy toll even for the strongest of elf women. I love how he is so loving and supports her here. From what I see in the fandom I think most people think Feanor is incapable of loving anyone else except his father, but I believe he wasn't always a cold bastard and had been a loving husband and father before the lies of Morghot.
In General, I conceived that it Nerdanel in early pregnancy twins.)
I am sure that he loved his family. In the end, otherwise he wouldn't have as many followers. Well, actually, it is lies of Morgoth, the death of father and a misunderstanding of the Valar eventually brought him great madness..