Perhaps he should have communicated his reason to her and not left everything so ambiguous and then the problem would have been averted. Open honest communication. Why cause all the needless worry and guess work? If she is asking about how youre feeling just tell her! IMHO he is torturing her, no doubt he knows she is the type who analyses so he should have just told her straight up... .sweetie I'm confused as to why my motorcycle won't start... . Easy and problem solved.
Correct it is miscommunication, but this is in itself is a lesser problem than she allowed it to build into. Often your pwBPD is simply likewise self focused on some all consuming issue, and that can send us into psychoanalyzing mode,. Not everything can be blamed on BPD.
I am not saying which one of these characters represents the pwBPD, as it can be applicable to either. Either can be guilty of catastrophizing miscommunication.
Open and honest communication can often be a casualty in relationships where fear of overreaction exists. This lack of easy openness can too easily become an avenue we use to project our own thoughts and fears onto others.