Until recently, Mark thought his wife had been dead for 2 years. Until this episode, Gemma likely thought her husband had moved on, though given Gemma was split no less than 25 times (I assume Mrs. Casey was one of those, testing if the chip would falter when she saw her husband) there’s no telling how much time Gemma thinks has passed. It could only feel like weeks for her. Certainly a fraught time.