Maybe punishment is a strong word here, rather unpleasant consequences.
You can't go with Jill without talking to Sage on the phone and she will ask you to come. This way you will either break your promise to Sage or refuse Jill's surprise party, negatively impacting your RP with her. Of course, this would not be a betrayal.
No, I mean if they accepted you and three of you started a throuple relationship and then you didn't choose them as LI in the ep.8.
If we're only talking about choices that block some routes, then I agree with you, messing with Cathy in Bella's car seems like the only example of such a choice. By the way, I never seem to have tried to avoid one of the girls in an M&J relationship, did that somehow backfire in chapter 9?