Can stress or anxiety cause vaginal dryness?

Yes, it can contribute. Lubrication is part of the arousal response, and stress, anxiety, distraction or fatigue can make it harder for your body to respond. That doesn't mean anything is wrong with you or your relationship. Slowing down, extending foreplay and using lube generously often help. If stress-related dryness is affecting your wellbeing, a clinician or sex-positive therapist can be a good ally.