The last time Betty visited Zing's, the food was excellent. Tonight is her anniversary and she was looking forward to an enjoyable evening

After the meal, she starts feeling that the service was not up to par and the evening was not as successful as she had hoped. According to the service-quality model, which gap is obvious here?

The gap prevalent here is the gap between perceived service and expected service. This gap occurs when the customer misperceives the service quality.