After bowling, Michelle will ask you to drive her back to her apartment. Follow the GPS route on your minimap. The drive back is usually shorter and less eventful than the drive to the activity.
Once you arrive at her apartment and park in the yellow marker, Michelle will exit the car. This concludes the mission. You'll receive a text message from her shortly after, indicating whether she enjoyed the date and if she's open to another one. Successfully completing dates improves your relationship with girlfriends, potentially unlocking special abilities.