Vaginal lubrication is the slip that appears with arousal as fluid moves through the vaginal walls and glands add their share. It reduces friction. It is also inconsistent. Stress, antihistamines, breastfeeding, menopause, and not enough warmup all dry the room out.

Lack of natural wetness is not a verdict on desire. Adding bottled lube is how adults solve a mechanics problem. Painful dryness that includes burning or cracking needs a look at tissue health, not only a larger bottle.

Arousal can be present with little wetness, and wetness can appear when the person does not want sex. Concordance is imperfect. Ask words, not only your hand.