Ford has a tiny, very shitty quality notebook that he kept hidden somewhere in his and Nimirylov's room. Nimirylov has vague memories or seeing Ford write in it in the past, but it's not that important. After Ford goes back through the portal, Nimirylov looks through their bedroom for anything of Ford's. That's when he finds the tiny, battered notebook.
Nimirylov frowns, tracing the cover of it gently before opening it slowly. Written there, in Ford's perfect handwriting is an entire record of the day they found out they were expecting Penni. For the next few hours, Nimirylov just sits there, carefully reading through this entire notebook. It documents Ford's entire pregnancy, as well as he could. After all, Ford's a scientist, an alien pregnancy, is certainly something for him to document. Nimirylov reads each word and relives each moment that's written in painstaking detail. The quality gets worse as it goes on, with Ford suffering through symptoms his human body certainly isn't made for, before improving again as Nimirylov realises that Ford documented the recovery period after birth as well.
Nimirylov doesn't know how to feel as he reads through it all. Does he feel the joy that Ford and he felt in the past when each stage was reached? Does he feel the sadness that Ford felt as he struggled through pregnancy? Does he acknowledge the way he still feels even now at seeing the hormonal things Ford wrote about him?
The book finishes with a hand drawn picture of Nimirylov dressing up a few months old Penni in one of the cute baby dresses he always put her in. The caption underneath just says "Mine" in that same perfect handwriting the book started in.
Nimirylov stares at it for longer than he can care to admit, trying to muster up any feeling towards it, but he's just empty. After all, no emotions will bring his husband back.