I don't know if they changed it over the updates, but maybe there should be gameplay pointers to avoid bad outcomes.
Once those pointers are ingrained into your strategy, you have more control how the game plays out instead of walking into undesirable outcomes due to lack of knowledge:
-Gwen:
Don't have her stand next to the 3 other guys, only next to Carwyn, Kobolt Joe or Vivian.
The other 3 guys also can't use their movement tech skills on Gwen like shove/swap/reposition.
-Carwyn:
(Only while transformed) Same as Gwen
(If one wants to pursue Gwen, avoid Vivian, but gameplay wise it doesn't matter since neither one will leave as long as they stay "uncorrupted")
-Vivian: Don't let her near the drones that you receive when Cythraul first joins, easiest is simply not use the drones at all.
(If one wants to pursue Gwen, avoid having Vivian and Carwyn close to each other, but gameplay wise, it's not important as neither one will leave as long as they stay "uncorrupted")
IIRC, they do give a quick warning about Vivian and those drones being "dangerous", but I remember many not realizing exactly what the warning meant and fall into this pitfall anyway or accidentally skipping/skimming over the warning.
Someone in the past wrote a good Gameplay Pointer:
Avoid giving EXP to anyone other than Carwyn, Kobald Joe, Vivian and uncorrupted Gwen.
Everyone else will betray you no matter what, so there is no point using them gameplay wise.