From what I can gather from the snippets, the characters in the game are:
1. The Male Doctor MC
2. Female Doctor's Wife MC?(Will she have her own POV?)
3. The Busty Tribeswoman
4. The Tribe boy
..The Chief or other Tribesmen hasn't been mentioned yet(Just pure speculation from the Comic version).
My guess is the Busty Tribeswoman is the Tribe boy's Mother, the Tribe boy seduces your Blonde wife and Male MC get to have soft-revenge by fucking the tribe boy's mother. So, yeah Camp with Mom style of storyline.
Blonde Wife x Tribes boy
Male Doctor MC x Tribemommy
The storyline could pretty much be that simple.
But, I'm still holding out hope we get the Chief and the other Tribesmen taking turns.