I have seen pictures of Nicholas and Ella as Onegin and Tatiana from Eugene Onegin, as well, but their costumes were different than those in the posted photo.
I'm not sure which play, assuming that we are correct in our guess, this photo would be from. The costumes look a little odd to me, only because Nicholas' appears to be evocative of the mid-1600s, while Ella's seems to represent an era of at least 50 years later (if not more).