itch.io

that's simple, first off don't go to the porch and give beer to Josef, second actually have the first sex scene with Isabella, go to the office of Josef and talk to him about her, it is implied she was his ex-wife, he then joins you on the second meeting with Isabella, it is here that after it dialogue you can make josef leave without meeting him on the porch or push for the open relationship with anna and later with adrian.

you still can, that path is pretty much a shortcut.

that's easy, it is implied that he was once married to her.

as for how to trigger it, simply sleep with her once, then inform him, but do that before ever telling him about Starmaker, meaning bypass drinking with him on the entrance every Friday, a different scene triggers, which also triggers him going to talk with Anna and both admitting and opening their relationship, which also implies Josef starts sleeping with other women.

basically a shortcut to keep Josef around.