I found out thats feeding by tube session cant be "forced" by Girl feeder. There is no resist check you simply deny it . Also how about some kinda willpower or Gluttony stat? Thats will main part of all resist checks .maybe 75 of willpower and 25 of girl relationships.
Good idea regarding a willpower/gluttony stat! Resistance chance vs feeder girls is wholly based on affection at the moment, so it does make sense for there to be an additional component to that. I might reuse the appetite system used for the NPC girls to keep it consistent.
I can certainly add a chance to fail resisting the tube sessions. I'll include that in the polishing update I'm currently working on.