IMHO the pregnancy image cannot be from the cheating path. The MC and Julia look content in it, something I doubt will happen on the cheating path which is on the way to a big confrontation. In addition, on cheating you can have a romance with Jasmine and can also get her pregnant. So very different from these pic. I estimate that the image is from the vanilla, sharing or cuck paths. If vanilla, it is also a vanilla path with comparatively high CP and shared fantasies, since Julia is wearing red.
As for who is the father: On vanilla it surely is the MC, anything else would make no sense. On vanilla/sharing (a subpath of vanilla with optional "sidefun"), Sharing and cuck paths, it could be any male, be it MC, Cornell, Rufus or one of the party guests.
On vanilla/sharing and sharing it will certainly be the players choice who will become the father, on the hard cuck route and cheating it will be more likely Cornell and/or Rufus and guests. On the less hard cuck route (you can decide during the dance) I theorise it will be like on sharing and the players choice.
If Dimaijo wants to mess with us, he also could let a superfecundation happen, meaning 2-3 dads, where they fertilize one egg cell each. In this case would have to happen at the party, since for such a rare event to happen, you need specific situations.