Season 3, Episode 22:
Dog With Two Bones
As Moya travels to a Leviathan graveyard to scatter Talyn's remains, the crew begins to fragment and scatter off to their new life paths. Crichton tries to imagine a life in which he can have Earth and Aeryn and comes to the realisation that he'll have to choose which is more important. However, Aeryn is still grieving the death of her Crichton and has trouble bringing herself to accept the situation as it stands. At a crossroads, they choose to let fate decide and flip a coin -- the result is tails, and Aeryn leaves in her Prowler.
Crichton decides to leave Moya as well and use his wormhole knowledge to find Earth. As he waits in a module for a wormhole to open, the whisperings of Moya's newest crewmember, Noranti, make him realise exactly what's affecting Aeryn's behaviour: she's pregnant. Resolving to find her, Crichton turns his module around and heads back to Moya, only to witness the Leviathan getting sucked into a wormhole and disappearing, leaving Crichton alone in his module, in deep space with a finite supply of oxygen...